Features: Material:?Aluminum Camera?accessory Solid?metal?mount?lens?adapter?allows?for?Leica?M39?lens?use?on?M42?camera?body Specifications: Suitable?for?M39?mount?lens?M42?mount?camera Diameter:?4.2?cm Thickness:?2?mm Net?weight:3?g Color:?Black Package?Content: 1?x?M39-M42?step?up?lens?Adapter