Built for shooters who demand the best, Sprinco's extractor springs go through intense heat treatment and cryo-processing, then get a slick moly-disulfide finish for unmatched reliability and wear resistance in your bolt carrier group. The XP 5-coil spring provides a greater load capacity compared to standard OEM springs, thereby eliminating the need for additional D-Fender rings or CRANE viton O-rings Sprinco's Extractor Springs undergo heat treatment and cryogenic processing to enhance durability They are capable of withstanding temperatures up to 750 deg F without any degradation in performance The 5-coil spring is compatible with all 5.56x45mm barrel lengths However, it may exert excessive force on rifles with barrels longer than 18 inches or on bolts with tight tolerances, which could potentially damage case rims