Put the ball from my Cordless Optical TrackMan into the Deft Pro and it's considerably smoother. : r/Trackballs
A size comparison between the Logitech Cordless Trackman Optical, the Microsoft Trackball Optical, and the Elecom Huge, for if anyone is curious. : r/Trackballs
Logitech Cordless Optical Trackman T-RB22 + Receiver Black on Black CLEAN TESTED | eBay
Mouse Ball Trackball 1.69'' Fit For Logitech Cordless Optical Trackman T-RB22 | eBay