Flat oval lens plate to mount 135mm and 150mm Rodenstock Omegaron and Ysaron enlarging lenses on the Omega D-5 and D-6 lens turret or #421-107 Slide-In Lensmount. For specific applications for this lens plate, please refer to our D-5 / D-6 enlarger Lens Mount Reference Chart. This lens plate is threaded, but the 50mm retaining ring supplied with the lens is required as a spacer - available separately if required.