I was interested in the vibration sensor and bought it, but it has been sitting unused. Even without a drum, when you hit something, there is a light and sound action triggered by the vibration. About 3 years ago, when I checked the operation, I found that the old batteries had leaked, so I disassembled it once. Both speakers were broken, so I replaced them with similar ones and confirmed that sound is produced. Also, one of the switches was broken, so I replaced it with a similar one as well. I will wrap it in plastic for waterproofing and ship it.