It's surprisingly hard to find thumb trackball mice, so there aren't a lot of competitors for this design - but this is an excellent mouse. In my opinion, the best. I use the computer daily, and often for long periods of time. This mouse design keeps my wrist from becoming fatigued or sore, or developing carpal tunnel. Its design is fully ergonomic. The fact it remains stationary also makes it extremely convenient for using with a laptop anywhere you like. The trackball ball is very easy to pop out (there's a small hole at the bottom of the mouse through which to do so) and clean with a microfiber cloth, along with the sensors in its bed which can easily become gunked up (no matter how clean your hands seem). A few months ago my cat knocked the mouse off the desk and one of the buttons popped out of alignment and wasn't clicking right. I dismantled the mouse's casing using a single small screwdriver and popped the plastic bits back into place and put the mouse back together without any issue. It's worked flawlessly again since. I just changed the battery for only the second time ever in Aug 2020, when I've owned the mouse since about Dec 2018. This is an unpopular opinion I guess, but I can't imagine gaming with any other mouse. No wrist fatigue, finite movement, and wireless to boot. Never had issue with lag or anything. The wireless USB dongle supports other Logitech wireless devices, so you only need the one dongle if you use a Logitech wireless keyboard or other peripheral. Super convenient. There is also a spot inside the battery compartment to store the USB dongle for convenient storage or for transit. The dongle is so small, however, I'm always able to get my laptop's case on with the dongle still plugged in. (How many times can I say "dongle"?) The Logitech software allows you to customize its sensitivity and button functions along with a ton of other settings. Super handy. If and when this one stops working, I will be buying another one.