The Glockmeister Gen4 grip plug (BCIG4LG) works on the following Gen4 GLOCKS: 20, 21, 40 and 41.
The Glockmeister grip plug secures in the frame utilizing the lanyard hole. It will keep dirt and debris out of the trigger area as well as help lead the magazine into the mag well.
PLEASE NOTE: This grip plug will NOT install on a Gen 4 or 5 that is using any of the additional backstraps. If using backstraps, please see the Pearce PG-FI21.