<ul> <li>Front side - 52.5 mm inner diameter</li> <li>Rear side - M55x0.75 male thread</li> </ul> <p>This adapter allows using projection attachments that have 52.5mm barrel diameter on lenses with M55x0.75 filter thread.</p> <p>Known compatible attachments are:</p> <ul> <li>ISCO Ultrastar Studio 80mm</li> </ul> <p>The adapter is secured by 3 of M5 screws. Improvement over previous version is intermediate flat spring to protect a lens body from damage by screws.</p> <p>Made of light alloy, anodized to black color and laser engraved.</p>