FM Series multi-purpose frequency/tacho/line speed meter Features： Simple row of 4 digit(FM4) or 5 digit(FM8)LED display Thrumb switch setting Control Mode: Up-up, Up-Down, Down-Up, Down-Down Auxiliary power:DV 12V optional dimension: 48W?8H?02L MM;96W?8H?00L MM Power : FM4：90～250VAC FM8: 220/110V AC more or less 15% Multi-function: The instrument can be used for measuring frequency tacho and line speed. The instrument has optical isolation and high anti-interence.