AR-15 MISSING PARTS KIT FOR LOWER RECEIVER One convenient kit for all the little parts that tend to get lost or need replacement during builds. Great as a replacement kit to keep on hand when out in the field. Includes Buffer retainer (1) and buffer retainer spring (1) Takedown / pivot pin detents (4) and springs (6) Selector detents (2) and springs (2) Disconnector springs (2) Bolt catch springs (2) and plunger (1) Mfg: Kak Industry Llc.