HE Hi-Low grenades have an impact fuse. Their generic damage profile is 6d20 EXP-DMG | 1 PEN | M. EXP.
During WW2, the Deutsches Heer invented a new method of propelling firearm projectiles deemed the "hi-low" propulsion system. Beginning in the mid-1960s the United States Army has begun issuing 40mm grenades utilising this principle to its troops in Vietnam and elsewhere. HE grenades of this type pack a mean punch with very little recoil, and are set to revolutionise infantry tactics. Furthermore, some vehicle-mounted weapon systems also make use of this ammunition, most famously the automatic grenade launcher on-board of AH-1 "Cobra" attack helicopters.