Bought a set of 4 for my 2002 Honda Civic Si. The size of the studs on my car is 4x100. It was just what I needed when I bought a set of spare wheels and snow tires. The new steel wheels I bought didn't match my hubs. 5mm is the exact thickness to solve this problem on my car, but don't stick out so much that it looks like a Super Mario Cart. The fit of the spacers was ok. They are universal so I wasn't expecting an exact fit. I mounted the wheels on spacers, tightened the nuts, and cruised around town and then out of town at speeds up to 80 mph. No weird vibrations, no noise and the steering was firm.