U.S. SOCOM (Special Operations Command) has had a scalable offensive hand grenade developed and has spent over $40 million buying large quantities. Scalable refers to grenades that can have different amounts of their explosives removed by the user to produce different results. With the minimal charge the grenade is basically a “flash-bang” that is meant to disorient (with a loud noise and bright flash) people, not really kill or injure. By adding 1-3 additional “increments” of explosives the user makes the grenade effective over a wider area and potentially lethal. These scalable grenades depend on explosives to injure, not fragments. They are also a lot more expensive, but for SOCOM operators the additional flexibility is often the difference between success and failure in an operation.
American Offensive hand grenades have been around since 1918, when they were invented for troops fighting in close quarters (enemy trenches). It was found that these grenades were also useful inside buildings and caves. Thus the Mk3 grenade kept getting upgraded and was the basis of the scalable version. The current Mk3A2 is made of waterproofed fiberboard with minimal metal components. The Mk3A2 weighs 440 gr (15.4 ounces), has a five second fuze, and contains 228 gr (8 ounces) of TNT.
Stun (or “flash bang”) grenades were invented for British SAS commandos in the 1960s. These weapons do not use explosives but rather have a fire and shatter proof body with perforations for momentary bright light and a very loud noise to escape. The effect is most intense 1-2 meters (up to 6 feet) from the detonation. A current example is the U.S. M84 stun grenade. This weighs 236 gr (8.2 ounces), uses a 4.5 gr (.16 ounce) magnesium/ammonium nitrate mixture, and a 1-2.3 second fuze to generate up to 180 db of sound and 6-8 million Candela of light for up to 1.5 meters (5 feet away).