Genustech Clamp on Adapter Ring (95mm) The Genus G-COAR 95 Clamp-On Adapter Ring for lenses with a 95mm diameter lens barrel. For use with Genus Production Matte Box (GPMB and GPMB-Kit). For Elite Matte Box use the Genus Elite GEM-COAR 95mm Clamp-On Adapter Ring instead.