High contrast cartridge alignment protractor improves visibility and eliminates tracking errors. Avoids overshoot distortion to maintain high quality sound Link to turntable setup guide with instructions printed directly on the protractor. Suitable for S-arm and any 1/2 inch mount cartridge. Colour:As Shown Material:Acrylic 100% Brand New, High Quality. Dimensions: Length 21cm/8.27inch, Width 5cm/1.9inch 1. Place the protractor on the turntable plate with the hole on the spindle. 2. Move the cartridge/tonearm until the stylus is exactly in the center of the bullseye. Check that the cartridge is square to the outer grid lines. - If not, loosen the cartridge mounting screws and gently twist the cartridge until it is square. 3. Move the cartridge/tonearm until the stylus is exactly in the center of the inner bullseye, twisting the protractor as needed. Check that the cartridge is square to the inner grid lines. - If not, change the overhang (move the cartridge inward or outward along the axis) until the cartridge is square. 4. Repeat steps 2 and 3 until the cartridge is square at both points. Tighten the mount and recheck as above. Remove the protractor. Relax and enjoy! Package Contents: 1 * Vinyl cartridge calibration ruler 1 * Magnification card Only the above package content, other products are not included. Note: Light reflection 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.