Pro-Ject Speed Box S Phono Speed Regulator, Black High-precision quartz-regulated electronic speed control governed by smart microprocessor Provides clean power decoupled from mains interference Allows for automatic speed change between 33 & 45 RPM (78 RPM possible with optional accessory pulley) Suitable for all Turntables with 16 VAC) Motors and up to 3 watt max. Power consumption Metal case shields electronics from vibration and electromagnetic interference