<ul> <li>Front side - M44x1 female thread</li> <li>Rear side - M52x1 male thread</li> </ul> <p>Made of high quality aluminium alloy.</p> <p>This adapte allows mounting lenses with M44x1 thread into focusing helicoids with M52x1 thread.</p> <p>Known compatible lenses:</p> <ul> <li>Bausch Lomb Tessar Series 1C (Patent Feb 24, 1903) 3 1/4 x 4 1/4</li> <li>Carl Zeiss Jena Tessar f/4.5 12cm</li> </ul> <p> </p>