Printable plugs for gluing 22lr barrel liner into printed barrels. One plug is sized for the chamber (marked B on the base for Breach) and the other is for the muzzle end (marked M on the bottom). These should fit very snugly in either end to keep JB weld out of your liner while you glue it in place. If its TOO snug, you can scale in slicer. These should be treated as one time use, and a fresh set printed for each barrel liner you glue in. The thickness of the rim is 1mm to mimic a 22lr round so you can also use the plug for liner spacing against bolt face