Instructions: 1. Place this protractor on your turntable platter with hole over spindle.2. Move / tonearm until stylus rests exactly on center of . (120.9mm radius). Check that is square with outer grid lines. - If not, loosen mounting screws and twist lightly until it is square.3. Move / tonearm until stylus rests exactly on center of inner -eye (66.04mm radius), Rotate protractor around spindle as required. Check that is square with inner grid lines.If not, change overhang, (move in or out along the axis) until is square.4. Repeat and 3 till is square at both points. Tighten mountingFeatures: High alignment protractor provides improved visibility and eliminates tracking errors.Avoids the over- distortion to keep high quality soundLink to turntable setup guide with instructions included, directly on the protractor.Works with an S -Shaped arm and any 1/2inch mounted .Extra magnifier make you more clear when adjusting the overhang.colour: whiteMaterial: acrylicsize: 19x4cmPackage Contents:1 x Overshoot ProtractorOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.