Pros: It's a wireless trackball. Great for work in the field when there's not surface to use a standard mouse. Also works well when using AutoCAD.

Cons: I ordered two of these refurbished M570 Trackballs at the about a month ago. One of the two was visible damaged. Customer service was friendly and initiated an RMA. Two weeks later, I had a replacement that worked.

Overall Review: I have used these trackballs for years for work since I am often out in the field with no flat surface to use a standard mouse.

Pros: 1) The sensitivity button is very handy. I use it to change the sensitivity depending on what game or program I am playing / using. Also, very useful when sniping in FPS games. 2) The G100s feels smoother than a standard mouse.

Cons: Nitpicking: The location of the sensitivity button... When trying to change sensitivity quickly for sniping, an alternate location for the thumb may have been better. But I am coming from a standard mouse that did not have this option, so like I stated, this is just nitpicking and not a major con.

Overall Review: IMO, the G100s is great for FPS, RTS, TBS, Spreadsheets, Documents, AutoCAD, ...