The smaller bombs had either Amatol or TNT while the larger bombs were filled more powerful explosives like RDX and Trialen to compensate for their reduced charges. The PC series of bombs were fitted with a time delay fuze which detonated the bomb after it had pierced a target destroying it with a combination of its blast and fragments. The PC series served as a base for the later PC RS series rocket propelled bombs which were designed to enhance penetration by increasing their terminal velocity.