A very useful accessory for most Pro-Ject turntables. The Speed Box II performs this change by the push of a button between 33 and 45 rpm. The quartz regulation and filter circuit gives a stable speed reference. With turntable Pulley SB (accessory) used with Speed-Box II or Speed-Box SE II, the following models can operate at 33/45/78rpm: Xpression, Debut III, Debut SE II, Debut III Esprit.