The phase 5 enhanced high performance buffer spring is designed for ar pistols and standard carbine applications.Extra power is provided with this buffer spring as well as durability.It also improves cycle operation which results in more consistent performance.The spring is constructed of a heat treated and corrosion-resistant steel wire.The enhanced buffer spring is for use with ar-15/m16 rifles or pistols chambered in.223/5.56mm.Type: Buffer SpringModel: Carbine EnhancedDimensions: 10.50"Material: Steel