The Enhanced Lower parts kit offers a convenient upgrade package for the AR15 for those looking for a complete Strike Industries solution for new builds, or to update their plain jane AR. This kit includes all the basics that you will need to build out your AR (minus grip).Features :Enhanced Bolt CatchStrike Magazine CatchStrike Magazine Catch ButtonEnhanced Pivot PinEnhanced Takedown PinSI Selector LeverSI Selector End PlateSI 60-90deg 3-in-1 Selector Shaft