Stroboscope disc with measuring light to check the actual speed Stainless steel disc Ø x height: 100 x 1mm Speeds: 33.3 rpm, 45 rpm. and 78 rpm. Measurement tracks for 50 and 60Hz Measuring light can be switched from 50 to 60Hz Battery type: 2 x 1.5V Ortofon SB-2 Stroboscope The SB-2 Stroboscope is essential for audiophiles to precisely tune the speed of turntable’s rotation for record music listening. Dimension – 67mm (W) x 68mm (L) x 22mm (H) Weight – 130g (with battery) Disc dimension – 100mm (dia) x 1.0mm (d) Disc material – Stainless steel Revolutions synchronized – 78 rpm, 45 rpm, 33-1/3rpm Housing material – Aluminum extrusion Battery – 2 x 1.5V (UM4) Accuracy of oscillation circuitry – 1/100 Hz, (0.1%) Originally packaged new goods from an authorized Ortofon specialist deal.