With 7/8 in washer to prevent overdrive and to increase holding value when fastening wood or thin metal to concrete or structural steel. Fits all Ramset, hilti, Remington and most powder actuated tools that use 22 cal single shots, 27 cal 10 shot strips and 25 cal discs. Shank diameter of 0.145 in.Washer increases bearing surface against the material to be fastened