Great for what they are, but I made the mistake of buying these for a motor with a smooth shaft (not a D-shaft). If you're in the same boat, I'd strongly suggest going for a clamping shaft such as this one: https://www.robotshop.com/ca/en/actobotics-5mm-bore-077-aluminum-clamping-hub.html These are made by Servocity (USA), but international shipping to Canada is expensive ($25), so you're better off buying them here.