This is a Lens Ring Adapter, Working diameter 40mm 50mm,,Applicable to 120X 180X 300X working diameter 50mm Monocular c-mount lens.
Model: Video C Mount Microscope Camera Monocular Lens Ring Adapter
Inside Diameter: 50 mm 42mm
Outside Diameter: 50mm 58mm
Working Diameter: 50mm 40mm
Material: Metal
Package Including:
1 x 40mm 50mm Ring Adapter