Scope wheel designed to fit the Discovery VT-2 Scope.
Rather than using a grub screw that digs into the scope and causes marks, these work by simply pushing the wheel onto the knob and tightening the bolt to clamp the mount together.
The overall diameter of these wheels is roughly 81mm and are offset roughly 6mm to allow the wheel to miss your scope mounts.
They are available in black, red, green and blue.