Seekins Precision Enhanced Bolt Catch, Black Finish, Drop In Upgrade For Any MILSPEC Lower Receiver 0011510057 The Seekins Precision Enhanced Bolt Catch is an easy to install upgrade that improves the functionality of any Mil-Spec lower receiver. Designed to make bolt manipulation easier" the unique" oversized bolt catch has an aggressive" diamond texture for positive operation. (Not compatible with AR-10 platform.)