Summary: This is the third one I have owned. The first one was one of the original versions. I now have two of the present version. My CNC machine was corrupting the mouse at my workstation with saw dust, so I got the same Trackball as the office.
this is by far the best input device on the planet
Phil M, Amazon
29 March 2016
Summary: After 28 years of IT experience, this is by far the best input device on the planet. Not used to trackballs? This is worth 3 days of 'training' yourself. Of all the trackballs, this is number one. Period. I still have the originals with the ball bearings instead of the light sensors. Best.
Works Better Than The Old Turbo & Expert Trackball Mouse
Bill Holtcamp, Amazon
22 March 2016
Summary: As a user of the old Kensington Turbo & Expert mouses my expert mouse would not work on my new PC - (no software) so I purchased the new expert mouse - works great - yes the ball is stiff out of the box but like I use to do on the older models - just wax your ball with some good automotive car wax 2...
Summary: I"m using this right now and I love this mouse. I've been through all kinds over the years with my desk job. Standard mice, joystick mice, and now this one. I really starting feeling carpal with a standard mouse and changed to the joystick.