DPMS A R Tactical Bolt Catch
I have verified these are original Milspec sized in width , depth and height with only the pads oversized.  Please verify your upper and lower is Milspec 5.56 and these will fit and work correctly.  I have been selling them for over 10 years and they have been on the market over 20 years.  If your upper and lower are machined in spec they will fit and function properly.