Generation 4 Sure Plug for Glock 17, 19, 22, 23, 31, 32, 34, and 35 Aid in guiding the Magazine into the Magazine Well Flush fit to eliminate the possibility of snagging on the open cavity Stops dirt and debris from entering the backstrap channel Note: You can not use the additional backstraps when the plug is installed. Sure Plug brand is distributed exclusively by Molon Labe LLC