Quality.

I bought a 6-wheel 110mm set, 3 right and 3 left. They arrived in 6 days. Visually, there is no difference between them, just a mark on the cardboard opposite the one for which side. 2 wheels were glowing brightly, all the others were weak, one did not glow at all. I recharged them, and one of them had a dead battery, so I replaced it, and it glows just fine. The wheels slide well, now I can practice my powerstop. They switch on and off when you press them.