Fotga Lens Mount Adapter for Leica M39 Mount Lens to M42 Screw Mount Camera Solid metal mount lens adapter allows Leica M39 lens use on M42 camera body Male thread: 42mm Female thread: 39mm Compatible Cameras:M42 Mount Camera Compatible Cameras Lens:Leica M39 Mount Lens Package included: 1 x M39-M42 Step Up Lens Adapter