Genustech GARD Lens Adapter Ring, D-Nut for GML and GWMC Matte BoxesGenustech GARD Lens Adapter Ring, D Nut for GML and GWMC Matte Boxes Slotting snugly into the back clamp ring of a Matte Box, the Genus Do Nut Adapter Ring (GARD) is a step down ring that bridges the space between the Lens Adapter Ring and the Matte Box. Made from high grade Delrin, the Genus Do Nut Adapter Ring features an angled inner lip that fits all Lens Adapter Rings from 52mm to 86mm. (Use on GWMC,GML ) Inside Diameter 95mm Outside Diameter