FTC robot 6mm shaft motors work so well paired to this
S25-16T 6mm Bore Aluminum Sprocket (am-3185) for chain drives, that more tooth sizes need to be made available - especially a 10-tooth version to allow wider ratio possibilities for single stage speed change
In addition, the introduction of a 4.7mm (3/16") bore size option that would work with both standard FTC flatted axles, or with upgraded case hardened ROUND axles would become very popular in no time.
Tetrix/Pitsco shaft/sprocket/hub stuff is overpriced, weak, and low performance/reliability. This design is robust, versatile, and worth the cost.
If a 4.7mm bore was offered, the OD of the split sprocket sleeve could still be matched to the clamp ring ID for interchangeability with 4.7mm axles OR 6mm motor sprockets.