These adjusters have a 1/4" of threads removed to allow the adjuster to fit into the unthreaded portion of the newer Anderson lowers that require a 3/4" grip screw.  By keeping a 1" grip screw there is better support of the internal set screw than using a 3/4" grip screw.  Comes with a lock washer.

Trigger Adjuster for use in Anderson lowers


AR 15 Trigger Adjusters