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 is designed for AR-15 bolt carrier groups and provides the same power as OEM springs but is optimal for use on 18" barrel rifles. 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 34 coil designFor AR-15 BCGMade from Chrome Silicon wire stockHeat treated, stress relieved, and cryogenically processedSpecifications:Weight: .1 ozDimensions: 1 x 1 x 2 in