The Mobile Fidelity Sound Lab GEO-DISC stylus alignment protractor makes cartridge setup easy. You will never realize the full potential of your cartridge without properly setting it up, but let's face it: Mounting and aligning a phono cartridge can be a tedious and time-consuming chore. Not with the GEO-DISC. Simply put GEO-DISC on your platter as you would a record, and align your cartridge using the simple printed graph based on the Baerwald alignment curve. It's that easy. Nobody with a turntable or vinyl LPs should be without this essential device.