This is a heavy-duty pin-tail focus rack for major brand stereo microscopes. It comes with a 3" (76mm) diameter of annular ring that holds microscope head. It is brand new in factory sealed box. Features & Specifications: Brand new heavy-duty pin-tail focus rack Good for major brand stereo microscopes Focus gear with coarse focus and tension adjustment Diameter of annular ring holding microscope head: 3" (76mm) Diameter of the pin tail: 5/8" (16mm) Focusing distance in vertical direction: 1-3/8" (35mm) Shipping Weight: 4 lbs Manufactured under ISO 9001 Quality Control Standard Excellent Five (5) Year Factory Warranty Unbeatable Low Price Guaranteed or the Difference Back! Satisfaction Guaranteed or Your Money Back!