Instructions: 1. Place this protractor on your turntable platter with hole over spindle.2. Move cartridge/ tonearm until stylus rests exactly on center of . (120.9mm radius). Check that cartridge is square with outer set of grid lines. - If not, loosen cartridge mounting screws and twist cartridge lightly until it is square.3. Move cartridge/ tonearm until stylus rests exactly on center of inner bulls-eye (66.04mm radius), Rotate protractor around spindle as required. Check that cartridge is square with inner set of grid lines.If not, change overhang, (move cartridge in or out along the axis) until cartridge is square.4. Repeat step 2 and 3 till cartridge is square at both points. Tighten mountingFeatures: High contrast cartridge 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, printed directly on the protractor.Works with an S -Shaped arm and any 1/2inch mounted cartridge.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.