Just like their buffer springs, the Sprinco AR-15 Extractor Springs are made from high quality Chrome Silicon wire stock that has been heat treated, stress relieved, and cryogenically processed to produce long lasting durability. This 4 coil extractor spring upgrade kit is designed for AR-15 bolt carrier groups and provides the same spring pressure as OEM springs for use in 18" barrel rifles. This upgrade kit also includes the Mil-Spec extractor insert and Viton O-rings. Whether you are replacing worn springs or setting some aside for future use, Sprinco springs are the only ones you will ever need.Features: Pack of 3 (9 pieces total) 4 coil design Optimal for 18" rifles For AR-15 BCG Made from Chrome Silicon wire stock Heat treated, stress relieved, and cryogenically processed Easy to install Includes Mil-Spec extractor insert and Viton O-Rings