Review on 📸 Cutting-Edge Digital Photo Laser Tachometer: Accurate Non-Contact Tach RPM Meter by Ian Bates

After some tests the thing doesn't work. It shows some random readings even when I'm pointing at my desk. -------- Just receiving this I can hear something inside falling apart. It makes noise when I shake it. So I opened it up and found a tiny tin ball rolling around (see photo). Don't check the quality at all before shipping? I'm assuming that tin ball is bad solder falling off the board. And of course the soldering on the board is just plain bad. The receiver (I think) even has a needle floating in the air. They must have hired an underpaid worker to do it. And the lens is a little dirty. Basically I have to disassemble this thing, clean it up before I can use it. Not worth the money.