Krak grenades are anti-tank weapons - the opposite of the anti-personnel frag grenade - they are designed to crack open armoured targets such as vehicles through a concentrated implosive blast. Although a krak grenade can easily kill a man, they are only used to attack tanks and other armoured vehicles. They are very effective at destroying hard targets, building structures, and for tearing holes into defensive structures. They are commonly used, easily obtained grenades, but not as effective at destroying armour as melta bombs.
The krak grenade must be placed on the target.
Krak grenades are commonly used by the Imperial Guard as well as many from other Imperial forces.