Every builder has launched a detent across the shop at least once. That's what this kit is for. It's a bag of the small springs and detents that go missing during a lower build, stocked deep enough that one kit covers several mishaps. You get the buffer retainer and its spring, takedown and pivot pin detents and springs, selector detents and springs, disconnector springs, and bolt catch springs and detent. Keep one on the bench and save yourself a trip. Kit Contents: Buffer Retainer (1) + Spring (2) Takedown/Pivot Detents (4) + Springs (6) Selector Detents (2) + Springs (2) Disconnector Springs (2) Bolt Catch Springs (2) + Detent (1)