Hardened bearing quality 440C Stainless steel ball for safety for Crosman 105, 106, MK1, MK2, and most Crosman guns. Crosman also used this ball on the bolts of some early guns, like the Model 114, etc. Also, used on the Benjamin pistols like model 130, 252, etc. When the Crosman V350 was first introduced this ball was also used as the BB retainer. Diameter .093"