This is a jewel tweezers for stereo jewelry/gem microscopes. It comes with 6 mm (in diameter) mounting thread. It fits most of the standard stereo microscopes on the market and all AmScope SE, SW & SM series stereo microscopes (the microscopes that have the model number starting with SM, SE or SW) Features & Specifications : Very Smooth Slide in the Sleeve Wide Open Clip for Holding Large Objects 3-Way Rotation Showing any Part without Touching the Objects Material: Metal Mounting Thread Size: 6 mm in diameter Compatibility: SE, SW & SM series stereo microscopes Manufactured under ISO 9001 Quality Control Standards