 A hardened penetration bomb with a reinforced casing and a delayed-action fuze, this allows the weapon to penetrate several metres into the ground before detonating, damaging fortified structures further underground.Developed from 1994, the Mod 11 went into service in 1997 replacing the older megaton-yield B53 bomb.About 50 Mod 11 bombs have been produced, their warheads converted from Mod 7 bombs.