Hello. Made a UGS stock for an airsoft gun. The back has a hole for the tank that will run all the way through, allowing the stock to be shorter. Has an arm bar guide if you have a UGS system that comes with one. The stock will fit tanks up to “52.3mm” wide. I made it this size because I had different tanks with different circumferences. If the print is slightly loose, I would add tape to the tank. (Don't block the arm guide with tape though.)