This Side Folder is compatible with 1-3/16 X 16 extension tubes. That is the standard thread for Milspec and Commercial extension tubes. However, some airgun manufacturers use non-standard thread patterns that will not be compatible with this part. Please confirm compatibility before purchasing. These are made by Leapers to be adapted to AK47s.
Please Note: These will not work with a conventional AR style buffer assembly. If you are looking to put this on a firearm you should do your due diligence before purchasing or get it from a firearm parts dealer who can help ensure compatibility.