"Made of tough, impact-resistant polycarbonate, the Bohning Blazer Double Lock Nocks feature a double lock, press-fit design, specifically made for shooters who use ""D""-loops. These nocks fit Easton Uni-bushing systems and standard carbon shafts without modification. The double-lock feature keeps the shaft on the string without affecting release for superior dependability and performance. Tough, impact-resistant polycarbonate Small, press-fit design Designed for use with ""D""-loops without affecting release"