The Strike Industries AR-15 lower Receiver spring replacement kit includes 9 important springs that are commonly replaced or easily lost when building stripped AR-15 lower receivers. The 9-Piece kit includes springs for the bolt catch, disconnector, buffer retainer, trigger, hammer, magazine catch, selector, and two detents. Includes:1 x Bolt Catch Spring1 x Buffer Retainer Spring1 x Trigger Spring1 x Hammer Spring1 x Disconnector Spring1 x Magazine Catch Spring1 x Selector Spring2 x Detent Spring FeaturesReplace worn springsCommonly used springsEssential for a gunsmith or AR owner