Zip Box Adapter Rings (49, 52, 55, 58, 62, 67, 72, 77mm) adapts lenses with threaded front rings sizes 49, 52, 55, 58, 62, 67, 72, and 77mm to the Zip Box 4x4 (80-85mm) and the Zip Box Double 4x5.65 (80-85mm). All adapter ring sizes are included with the kit! It is important to note that many lenses with a threaded front of 77mm can work natively in the Zip Box 4x4 (80-85mm) and the Zip Box Double 4x5.65 (80-85mm) because there exterior diameter is approximately 85mm when accounting for the lens hood bayonet, etc. Please check the list of compatible lenses on the Zip Box 4x4 (80-85mm) and Zip Box Double 4x5.65 (80-85mm) pages. Individual ring dimensions: 84mm exterior diameter x 6.5mm thick