This could be the next grenade of the US Marines

Nammo has developed a scalable hand grenade. The explosive power increases with each attached module. Due to the pressure generated, enemy forces are intended to be neutralized. In comparison to conventional M67 grenades, this grenade produces almost no fragments, resulting in less collateral damage. Therefore, the US Marines have shown great interest in this grenade, which already bears the designation MK21 Mod 0. The base with one module is enough to give people in a room a mild concussion. Two modules are enough to kill all enemies in the room. With three modules, even more explosives ensure that the room may collapse, according to the manufacturer's specifications. If you would like to learn more about it, you can find additional information HERE.

Nammo on the internet: www.nammo.com