The HE Grenade is a lethal grenade that explodes after a few seconds, it does 1-100% damage to players. The grenade can be cooked (held with the pin out) so it explodes shorter after it is thrown, but this renders the player vulnerable to enemy fire. You must switch to the grenade before using it, as opposed to thrown while holding the current weapon. The HE Grenade is useful for clearing out rooms or weeding players out of camping spots.
Not to be confused with smoke grenades.