1,Dimensions: The internal diameter of this adapter ring is 50mm / 2in, outer diameter is 80mm / 1in and the working diameter is 76mm / 3in. 2,Application: Microscope camera adapter ring is suitable for 120X 180X 300X monocular C mount lens with working diameter of 50mm. 3,Main Function: If you have a stereo microscope, this lens ring adapter can help to turn your stereo microscope to video microscope. 4,Aluminum Alloy Material: Lens ring adapter is made of high strength aluminum alloy, with good durability and stability, not easy to rust and deform. 5,Long Lasting: Exquisite workmanship, microscope monocular lens ring adapter has stable and reliable performance, with long service life. 1 x Microscope Ring Adapter1 x Hex Wrench Item Type: Microscope Ring AdapterMaterial: Aluminum AlloyInternal Diameter: Approx. 50mm / 2inOuter Diameter: Approx. 80mm / 3.1inWorking Diameter: Approx. 76mm / 3in Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.