The adaptor ring screws onto the camera's lens and, in turn, the filter holder clips onto the adaptor ring. The adaptor ring screws onto the lens with a fluid action, thanks to the sturdy construction and aluminium screw thread.
The wide-angle adaptor ring is suitable for use with wide-angle lenses. It differs from the standard adaptor ring by sitting closer to the front element of the camera's lens. As a result, the likelihood of vignetting is dramatically reduced.