Review on 🔧 Ultimate Power Transmission Enhancement: Inch Chrome Steel Bearing Balls for Top-Performance Bearings by Robert Hole

I ordered these for a marble coaster contest my son was entering. The rules state that he can use a 1/2 inch diameter glass or steel ball. I have a few 1/2" glass balls (I measured them with calipers) but thought a steel ball would be a better option. When it arrived it was significantly less than 1/2" in diameter. So useless on the route my son designed for a ball that is actually 1/2" in diameter. BEWARE.