The tool ​​​​threads onto the same place as where a second position Regina Corse/Oro, etc., sprocket fits. The primary use in my case is to remove the two largest sprockets on Regina and Atom freewheel bodies. They thread off from the spoke side and use reverse threads. As the sprocket is turned to loosen, the body threads in tighter on the tool. The threaded socket threads in from the other side and acts as a stop. You need to make certain the stop is adjusted so the freewheel body does not bottom out without engaging the stop. If it does, removing the body from the tool becomes challenging. I hope this is helpful. If it makes no sense maybe I can take pictures of it in action.