D|Focus Systems 82 to 58mm Step Down Ring

The D|Focus Systems 82 to 58mm Step Down Ring lets you attach the D/Focus Systems D/Matte Mattebox to any lens with a 58mm filter diameter. The D/Matte has an 86mm lens opening and comes with an 86 to 82mm step down ring. This 82 to 58mm ring that you've clicked into would attach to the 86 to 82mm ring and would thus create a step down from 86mm to 58mm.