This tool is designed to aid in trigger work for your AR-15.  The fixture uses .154″ pins.  It allows you to fully assemble your trigger parts so that you can see every part the the trigger mechanism (Fire Control) in proper relationship.  Great for Trigger Jobs, Learning how the trigger and related parts function, and gunsmithing.  Includes both stops for the safety to allow full function.  Kit comes as pictured, just add your parts.  This is a rental.  If you want to buy one email a request.