Replaces the stock firing pin with the newly designed and alloyed firing pin and spring. The design incorporates an engineered radiused shoulder that all but eliminates those broken pins. The alloy is MIL-SPEC the same as the M-16 and aftermarket AR-15. Minor fitting may be required. The pins are designed a little long so they can be fitted properly to each individual rifle. Complete instructions included along with a new firing pin spring.