1. Mechanical Metronome 2. Loud sound 3. Stable Metronome 4. Robust structure Piano Music Mechanical ... mechanical core,pure metal movement · Accurate beat with bell,stable, loud · Bell for beats 0,2,3,4 and 6 · Easy ... wear,durable,good stability. · a unique of the appearance,portable,loud and clear voice and simple operation ·alibaba golden supplier & manufacturerSpecification ...