This adapter allows using microscope objectives with M32x0.75 mount thread in front of lenses with M49x0.75 filter thread (for macrophotography purposes).
Made of anodized aluminium.
Important note: Some objectives with M32x0.75 mount like Bell & Howell Eymax fit fine. Others like Leica PL APO have rear part protruding beyond of the thread cylinder. Moreover, it moves back if you push front part of the objective. So, it will not fit a camera lens since rear part will not clear front glass element of the lens. Longer M32-M49 adapters with guaranteed clearance are available for such lenses therefore.