1304 Series 6mm Bore Face Tapped Clamping D-Hub
Clamp onto your axles for maximum hold. 6mm D-Bore means your axles will not rotate in the hub.
Clamp this hub before mounting wheels/gears/etc to the threaded holes. Screw accepts a 2.5mm hex.
No slip, no set screw, no more grooves in your axles.