Lee Standard Adaptor Rings feature an  aluminium  screw thread and attach onto the end of your lens to accommodate the Lee Filter Holder or Lens Shade (available separately). Simply screw the Adapter Ring onto your lens and the holder will clip into place by a smooth, quick release spring loaded mechanism. There are also Wide Angle Adapter Rings available and are a better match if you're using lenses wider than 35mm as this will stop any vignetting. Check the end of your lens to determine which size Adapter Ring you need to fit your lens. This Adapter ring is for the 100mm system and is compatible with lenses with a 77mm thread.