It allows you to attached threaded items (attachments) to the end of the barrel. If you have a stamp for a silencer from the ATF, you could add a silencer to the 22A.
Go to Hobby Lobby and buy some leather...Go on eBay and buy a sheet of Kydex (Easy to work with a heat gun) Mold it to you weapon and then use Chicago Screws to mount to leather...Attach nylon straps with commercial Velcro ends and make it to fit any vehicle...
You can make it to fit several...