This is a jewel tweezers for stereo jewelry/gem microscopes. It comes with 3 mm (in diameter) mounting thread. It fits all AmScope SH series stereo microscopes (the microscopes that have the model number starting with SH). 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: 3 mm in diameter Compatibility: SH series stereo microscopes Manufactured under ISO 9001 Quality Control Standards