Product Description: Mechanical metronome is a mechanical device that emits a stable beat at various speeds, helping you to develop your own sense of rhythm. Internal clock structure with gears and winding drives a pendulum; at the end of ecah pendulum swing, it produces clicking sound, the speed of which can be adjusted based on that the weight slides up the pendulum rod to decrease or increase the tempo; the speed is 40-210 beats per minute. Parameter: 1. Product size : about 20.5 * 10.2 * 11.2 cm / 8.07 * 4.01 * 4.41 in 2. Material: plastic, metal 3. Color: Transparent blue 4. Packing: carton Package Content: Metronome * 1 Instruction Book * 1