High-quality auto transformer series provides the advantages of excellent frequency response, low insertion loss and reliable performance for volume control application in 25 and 70.7-volt systems. Attenuation is accomplished in ten make before break steps plus positive off position. (No stop between maximum and off position to prevent switch damage). Contacts are silver plated for noise-free operation. Features a removable terminal block. Includes stainless steel plate, with stamped and filled or screen printed dial scale and a skirted black knob.