Trusted by professionals, Sprinco's extractor springs are precision-wound from chrome silicon, stress relieved, cryogenically treated and finished with a moly-disulfide plating - built to exceed mission-critical demands. The AR .308 Cal dual extractor CS spring upgrade kits from Sprinco USA incorporate springs made from heat-treated, stress relieved and cryogenically processed chrome silicon wirestock These springs are further enhanced with a molybdenum disulfide coating The XP 5-coil spring provides a greater load capacity compared to OEM springs, thereby removing the necessity for D-Fender rings or CRANE viton O-rings It is compatible with all 5.56x45mm BBL lengths These springs sustain performance under extreme duty cycles and temperatures reaching up to 750 deg F The dual spring XP .308 Cal sets are compatible for use with or without CRANE O-rings