Get your 'bot rolling with this durable and smooth steel ball caster. We like the size (not too big, not too small) and surprisingly fluid motion of this caster. It's also really easy to attach, with two screw mounts that will allow you to attach it to any chassis material. Note that it doesn't come with any mounting hardware, use 4-40 or M3 screws to attach to whatever you like.
Matches perfectly with our purple metal chassis, but can be used for anything where you want 20mm of height.
We also have a smaller ball caster, with 16mm height, for little bots!