The classic metronome to sit on your piano, with the weighted timer, just lift the wait up or down to make the speed faster or slower. Everything is mechanical, a wind up mechanism will last for a long period of time.
Having this will keep you in time with your music pieces or help you to further understand timing and rhythm with music.
The Hemingway metronome is of great quality, it is a plastic gloss finish with gold set timer and knobs. A beautiful piece to accompany your piano.