The sound performance of any turntable begins with precise rotational speed adjustment and accurate phono cartridge alignment. The Oracle Calibrator disc is a universal arm/cartridge precision protractor and a convenient full-size strobe disc. The Calibrator disc features two sets of two bands to adjust the 33rpm and 45rpm speeds and this for both 50Hz and 60Hz power sources. The disc also comes equipped with a millimeter alignment grid to help align your phono cartridge such that its perpendicularity with the record's groove is optimal. Please make sure to read the user manual provided on our website for user instructions. The Oracle Calibrator disc is an essential tool to have!