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 Catch Strike Magazine Catch Strike Magazine Catch Button Enhanced Pivot Pin Enhanced Takedown Pin SI Selector Lever SI Selector End Plate SI 60-90deg 3-in-1 Selector Shaft