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At a glance
GBU-39 Small Diameter Bomblarger figure on 2 of 2
M18 smoke grenadelarger figure on 0 of 2
Counts only measures both sources give with the same scope. A larger figure is not a better system.
Measured figures
Length
Single source70.8 in (1.80 m)[source]
Length
Single sourceConfiguration
| Specification | GBU-39 Small Diameter Bomb | M18 smoke grenade |
|---|---|---|
| Type | Glide bomb[source] | Smoke grenade[source] |
| Place of origin | United States[source] | United States[source] |
| In service | 2006–present[source] | 24 September 1943-present[source] |
| Used by | United States Israel Italy Netherlands Ukraine Saudi Arabia Australia[source] |
5.75 in (146 mm)[source]
packed
Single sourcewings extended
Single source5 ft 3.3 in (1.61 m) (wings extended) 7.5 in (190 mm) packed[source]
Operational; All SDB I variants over when air-dropped
Single sourceOperational; when launched as a part of the GLSDB
Single sourceAll SDB I variants over 60 nmi (69 mi; 111 km) when air-dropped, 150 km (93 mi; 81 nmi) when launched as a part of the GLSDB ,[source]
AFX 1209 MBX ("multiphase blast explosive"), composite case Laser SDB (GBU-39B/B)
Single sourceAFX 757 enhanced blast insensitive explosive, penetrating steel case
Single sourceAll SDB I variants total SDB I (GBU-39/B)
Single sourceExplosive fill AFX 757 Insensitive munition certified PBX Penetration: greater than 3 ft (0.91 m) of steel reinforced concrete SDB FLM (GBU-39A/B)
Single sourceAll SDB I variants 206 lb (93 kg) total SDB I (GBU-39/B) Explosive fill: 36 lb (16 kg) AFX 757 Insensitive munition certified PBX Penetration: greater than 3 ft (0.91 m) of steel reinforced concrete SDB FLM (GBU-39A/B) 137 lb (62 kg) AFX 1209 MBX ("multiphase blast explosive"), composite case Laser SDB (GBU-39B/B) 36 lb (16 kg) AFX 757 enhanced blast insensitive explosive, penetrating steel case[source]
Filling weight
Single source11.4 oz (320 g)[source]
Bars compare reported quantities only. A larger figure does not make a system better; configurations and test conditions differ.
United States Australia Iraq New Zealand South Vietnam Ukraine[source] |
| Wars | War in Afghanistan , Iraq War , Military intervention against ISIL , Syrian Civil War , Russian invasion of Ukraine , Gaza war[source] | World War II Korean War Vietnam War War in Afghanistan (2001–2021) Iraq War Russo-Ukrainian War[source] |
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| Manufacturer | Boeing Integrated Defense Systems[source] | Pine Bluff Arsenal[source] |
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| Unit cost | US$40,000 (SDB I, FY 2021)[source] | $109.02 (avg. cost in 2025)[source] |
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| Produced | 2005–present[source] | 1943-present[source] |
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| No. built | 17,000+[source] | 3,800,000+[source] |
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| Variants | GBU-39/B GBU-39A/B GBU-39B/B[source] | G940 (Green) G945 (Yellow) G950 (Red) G955 (Violet)[source] |
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| Warhead | SDB I (GBU-39/B) penetrating blast fragmentation, penetrating steel nosecone SDB FLM (GBU-39A/B) blast ultra-low fragmentation Laser SDB (GBU-39B/B) penetrating blast fragmentation, w/o steel nosecone[source] | — |
|---|
| Guidance system | SDB I (GBU-39/B) SDB FLM (GBU-39A/B) GPS / INS Laser SDB (GBU-39B/B) GPS / INS with terminal semi-active laser guidance[source] | — |
|---|
| Accuracy | SDB I (GBU-39) 3 ft (1 m) CEP[source] | — |
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| Role | 250-pound (110 kg) precision-guided glide bomb[source] | — |
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| Source measurement | The GBU-39/B Small Diameter Bomb ( SDB ) is a 250-pound (110 kg) precision-guided glide bomb that is intended to allow aircraft to carry a greater number of smaller, more accurate bombs. Most US Air Force aircraft will be able to carry (using the BRU-61/A rack ) a pack of four SDBs in place of a single 2,000-pound (910 kg) Mark 84 bomb . It first entered service in 2006. The Ground Launched Small Diameter Bomb (GLSDB) was later developed to enable the SDB to be launched from a variety of ground launchers and configurations.[source]GBU-39 Small Diameter Bomb · Lead; only the objects and conditions stated in this passage The small size of the bomb allows a strike aircraft to carry more of them than previously available bombs, and thus strike more targets. The SDB carries approximately 36 lb (16 kg) of AFX-757 high explosive . AFX-757 is an insensitive enhanced blast polymer-bonded explosive , containing 25% RDX high explosive, 30% ammonium perchlorate oxidizer, 33% aluminium powder , 4.44% HTPB binder and 6.56% dioctyl adipate plasticizer. AFX-757 has improved air blast equivalent, 1.39 times more than Composition B , but low brisance due to low RDX content. It has integrated "DiamondBack" type wings which deploy after release, increasing the glide time and therefore the maximum range. Its size and accuracy allow for an effective munition with less collateral damage . Warhead penetration is 3 ft (1 m) of steel reinforced concrete under 3 ft (1 m) of earth and the fuze has electronic safe and fire (ESAF) cockpit selectable functions, including air burst and delayed options.[source]GBU-39 Small Diameter Bomb · Description; only the objects and conditions stated in this passage The SDB I has a circular error probable (CEP) precision of 3 ft (1 m). CEP is reduced by updating differential GPS offsets prior to weapon release. These offsets are calculated using an SDB Accuracy Support Infrastructure, consisting of three or more GPS receivers at fixed locations transmitting calculated location to a correlation station at the theatre Air Operations Center . The corrections are then transmitted by Link 16 to SDB-equipped aircraft.[source]GBU-39 Small Diameter Bomb · Description; only the objects and conditions stated in this passage In January 2016, the Air Force awarded a contract to Scientific Systems Co. Inc. to demonstrate the company's ImageNav technology, a vision-based navigation and precision targeting system that compares a terrain database with the host platform's sensor to make course corrections. ImageNav technology has demonstrated target geo-location and navigation precision within three meters.[source]GBU-39 Small Diameter Bomb · Description / Alternative guidance and warheads; only the objects and conditions stated in this passage Under a contract awarded in September 2006, Boeing developed a version of the SDB I that replaces the steel casing with a lightweight composite casing and the warhead with a focused-blast explosive such as dense inert metal explosive (DIME). This should further reduce collateral damage when using the weapon for pinpoint strikes in urban areas. The USAF intends to use the same FLM casing on a weapon of 500 pounds (227 kg). Boeing celebrated the delivery of the first 50 FLM weapons on 28 February 2008 and delivered the last of the 500 FLMs under contract in December 2013.[source]GBU-39 Small Diameter Bomb · Variants / GBU-39A/B – SDB Focused Lethality Munition (FLM); only the objects and conditions stated in this passage In 2011 Boeing began testing on a laser-guided version of the baseline SDB, integrating the same Semi Active Laser (SAL) from the GBU-54 Laser JDAM. Boeing claimed to have successfully hit targets moving at 30 mph (48.3 km/h) and 50 mph (80.5 km/h).[source]GBU-39 Small Diameter Bomb · Variants / GBU-39B/B – Laser SDB; only the objects and conditions stated in this passage In August 2024, CNN reported that Israel used the GBU/39 again in the Al-Tabaeen school attack , killing over 90 people according to the Gaza Civil Defense. The IDF stated that it was a precision strike against a Hamas command and control center that killed at least 19 Hamas and PIJ militants.[source]GBU-39 Small Diameter Bomb · Operational history; only the objects and conditions stated in this passage | The M18 Colored Smoke Grenade is the standard issue colored smoke grenade of the United States Armed Forces and is produced by the Pine Bluff Arsenal . Development began in 1942 after the Army Ground Forces requested a smoke hand grenade be made that had a visible range of 10,000 feet and could be used for marking friendly troop positions, identifying American tanks , or to signal location of downed planes . Utilizing previous experience in colored smoke signals, the Chemical Corps took on this task and had the first colored smoke grenades available in April 1943 designated as "M16".[source]M18 smoke grenade · Lead; only the objects and conditions stated in this passage In 1942, the Army Ground Forces requested a smoke hand grenade be made that had a visible range of 10,000 feet to be used for marking friendly troop positions, identifying American tanks, or to signal location of downed planes. Utilizing previous experience in colored smoke signals while cooperating with the Ordnance Department , the Chemical Corps took on this task. Development of colored smoke hand grenades began in September of that year.[source]M18 smoke grenade · Development History / Creation; only the objects and conditions stated in this passage First models of the smoke grenades were based on the M7 tear gas grenade, utilizing its tube and fuse assembly. This was a 2 + 3 ⁄ 8 -inches wide and 4 + 5 ⁄ 8 -inches tall steel cylindrical tube with 3 lines of 6 emission holes going around the body. On top were 4 additional emission holes, and a threaded hole in the center that a M200A1 fuse went into. The fuel mixture chosen consisted of sulfur and potassium chlorate . Sodium bicarbonate was used as a coolant to absorb heat, helping the dye mixture burn longer while preventing it from decomposing. Organic dye mixtures that varied in composition based on color were pressed into the tube before the fuel mixture was added.[source]M18 smoke grenade · Development History / Creation; only the objects and conditions stated in this passage Finding the right dyes took time, with hundreds tested at the Edgewood Arsenal and various other agencies. Many were discarded due to not meeting visibility and color requirements, or for being in short supply at the time. Rather than the dyes being synthesized by Edgewood Arsenal Laboratories, they were obtained from various industries because of the variety and quantity required. Development was finished once all colors could be distinguished from 10,000 feet. These grenades produced smoke for 2 to 2 + 1 ⁄ 2 minutes. They came in colors of red, orange, yellow, green, violet, and black and were designated as "M16" in April 1943, becoming standard issue and entering full production in May. |
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| Designed | — | 1943[source] |
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| Developed from | — | M16 Colored Smoke Grenade[source] |
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| Detonation mechanism | — | Pyrotechnic M201A1 Pull-ring delay Igniter (1.0–2.3 seconds)[source] |
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| Former operator · Australia | — | Australia[source] |
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| Former operator · Iraq | — | Iraq[source] |
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| Former operator · Poland | — | Poland[source] |
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| Former operator · South Vietnam | — | South Vietnam[source] |
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| Reported operators |
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Shortly after the production of the M16 began, the Army Ground Forces tested its performance and decided they wanted a more rapidly burning smoke grenade with a denser smoke cloud. This was not possible with the current composition of fuel and dye mixtures and would result in the dyes burning rather than volatilizing. Proportions of ingredients in the mixtures were adjusted, along with the pressure at which they were compressed during production. The rows of holes around the tube the mixtures went into were removed, and a 1 + 1 ⁄ 2 -inch hole was cut through the middle on the bottom.[source]M18 smoke grenade · Development History / Creation; only the objects and conditions stated in this passage
The new grenades produced the desired denser, more vibrant colored smoke cloud, and had a shorter burning time of about 1 to 1 + 1 ⁄ 2 minutes. They were designated as "M18" on 24 September 1943, entering full production and replacing the M16 which was then marked limited standard and stopped being produced.[source]M18 smoke grenade · Development History / Creation; only the objects and conditions stated in this passage
Originally they were to come in the same colors as the M16, including white. During later testing it was decided that orange and yellow along with blue and violet were too similar for aircraft to differentiate from altitudes of 10,000 feet. Black and white were discarded because being able to identify them from other battle-field related smoke would be difficult. This left the M18 being produced in 4 colors instead which was red, yellow, green, and violet.[source]M18 smoke grenade · Development History / Creation; only the objects and conditions stated in this passage
In the 1950s the tube for the M18 was 2 + 1 ⁄ 2 -inches wide and 4 + 1 ⁄ 2 -inches tall. There were 6 emission holes on the top and an additional on the bottom covered by tape for smoke to release when ignited. On the top a M201A1 pull-ring fuse assembly was threaded into the middle, and the top was painted indicating the color of smoke inside. A yellow band and text painted on the body stated the color, lot number , and date produced following MIL-STD-1168 format.[source]M18 smoke grenade · Development History / Subsequent Design Changes; only the objects and conditions stated in this passage
In the 1960s the M18 tube sized was changed to 2 + 1 ⁄ 2 -inches wide and 5 + 3 ⁄ 4 -inches tall. There were 4 emission holes on the top instead of 6, but the one on the bottom remained. The top was painted indicating the color, while the body came in gray or olive drab. A yellow or gray band and text were painted on the body. A waxed cardboard tube was used for shipping protection instead of metal.[source]M18 smoke grenade · Development History / Subsequent Design Changes; only the objects and conditions stated in this passage
When ignited and thrown, the top of the grenade with the fuse assembly detached while the ballute inflated. The grenade would then glide towards the ground upright, and could float in water. During testing it was found these versions of the M18 had a lower smoke volume but burning time was almost double of the standard M18 with 90 seconds minimum. Although testing was considered successful, this version of the M18 was not used outside of it. It was created as the standard M18 was found to provide poor visibility for signaling when used in areas partially or fully covered in water in Vietnam .[source]M18 smoke grenade · Development History / Non-submersible Variant; only the objects and conditions stated in this passage
The M18 is used by holding it in one hand with the safety lever pressed against the canister. The safety pin/ring is then removed after which the M18 can be thrown. As the safety lever is released, it is forced away from the body by a striker spring. The striker rotates on its own and strikes the percussion primer. The fuze delay then starts the ignition process. The tape covering the bottom emission hole is blown off and smoke is released. After ignition, the M18 produced a cloud of colored smoke for 50 to 90 seconds. The M18 could be thrown up to 35 meters by the average soldier.[source]M18 smoke grenade · Operation / Throwing; only the objects and conditions stated in this passage
To use the launcher, the stabilizer tube was installed over the grenade launcher at a position that would give a desired range. The grenade/adapter was rotated so that the safety lever faced the ground, and the safety pin was removed. The assembly was launched by firing a high-powered blank from the rifle. When fired a forceful shock causes the setback band to slide down the grenade, releasing the lever. After launching the assembly would remain attached to the grenade until it landed. Using the M2/M2A1 adapter allowed higher ranges up to about 180 meters.[source]M18 smoke grenade · Operation / Launcher Attachments; only the objects and conditions stated in this passage