These unguided high explosive bombs have been in the RAF's inventory for decades and their basic designs dates back to those used in the Second World War, adapted for use on supersonic strike aircraft.

General purpose bombs come in two types, the 505kg and a smaller 312kg version. The 505kg bomb forms the basic warhead used in the RAF's existing Paveway II laser guided bomb system, when provided with a laser seeker and guidance vane packages.

The larger of the two weapons can be used by Tornado GR4. The smaller 312kg is not used by Tornado GR4.

Both the 505kg and the 312kg weapon use unitary blast warheads and both can be dropped as freefall bombs or fitted with a retarder unit, which rapidly slows the bomb in flight, allowing aircraft to drop a bomb at low level over the target and get clear before detonation.

Both weapons have three modes of detonation. They can be preset to detonate above a target in airburst mode to provide the maximum fragmentation effect for attack of unprotected targets.

Another mode is impact detonation, for achievements of maximum blast damage to unprotected targets.

The final mode is post-impact delay, in which the bomb will detonate after a pre-set delay, allowing it to penetrate a target structure. The length of the delay can be varied to achieve the best effects against individual targets.