Cherub WSM-330 High Accuracy Mechanical Metronome (Black) WSM-330 is a Mechanical Metronome with Traditional demonstration of beat by wood block chip sound and 5-position on/off bell. Metronome' Tempo range: 40-208 bpm,Tempo Tolerance: 1%. Traditional tower shape, Vintage piano Metromome exterior. No battery needed,traditional Wind Up design, for Piano,Guitar, Bass, Drum, Violin Top-grade metal mechanisms and Hardness ABS shell,durable.