KensingtonOrbit Trackball Mouse with Scroll Ring (K72337US), 4 1/2X5 1/2X2"

I have a Logitech M570, Logitech Trackman Marble, Adesso Trackball, Kensington Expert, and the Kensington Orbit with scroll ring. Trackball experiences are very subjective because our hands are all different shapes and sizes, and we use different techniques. In my experience the Kensington Orbit with scroll ring is the overall winner.With regard to performance, the Kensington Expert is the best. It is also two to three times the price of all the other trackballs listed. Additionally, the Expert is tilted at a steep angle toward the user. This can put your wrist in an awkward and painful position. The Logitech Trackman Marble and the Orbit are both tilted slighty away from the user, and this is very comfortable. The scroll ring on the Orbit is also much smoother than the scratchtastic Expert.The Logitech Trackman Marble is the most like the Orbit. The trackballs are the same size and have a similar form. The shape of the Marble is more comfortable overall and has two additional programmable buttons. The Orbit has somewhat less comfortable button placement, and lacks the extra buttons. The Orbit can be programmed to emulate a middle click by pressing both buttons. However, the Logitech does not have any scroll wheel or scroll ring. That's an automatic disqualification in my book. The Orbit wins by default.The Adesso Trackball gets a number of negative reviews, and rightfully so. It has the most useless button placement I have ever seen. However, it does have a much larger ball than the Orbit and Marble, has a higher resolution (800dpi), has a scroll wheel, and is in the same price range. With a couple of modifications and the use of arm rest (I use a thick text book), it is a truly fantastic trackball. However, out of the box the Orbit and the Marble leave the Adesso in the dust.The M570 is a thumb controlled trackball. Many people love them, while others abhor them. (I happen to have no preference, and use both) If you have a predilection for a fingertip controlled ball, the Orbit and other trackballs win this round. Otherwise, the M570 is a top notch device.While the other trackballs may best the Orbit in one way or the other, it scores well in all areas. It gets my recommendation as the best overall affordable trackball.The rundownPros:-affordable-comfortable shape-smooth rolling ball-the best scrolling apparatus-a good sizeCons:-no extra buttons-no dedicated middle click button-slightly awkward button placement

I've had the trackball for about a month now. I bought it to replace the wireless Mighty Mouse that came with my Mac 'cause it ate batteries like no tomorrow. VERY, VERY pleased with the trackball. It took me about a week to figure out how to comfortably use it as I had exclusively using a Wacom tablet in place of the mouse, before deciding to get some sort of mouse.The software: To start off, for those reading reviews of those complaining about the program, you CAN plug and play it. You don't actually need the program for the trackball to work. The mouse adjustments that you can make in the System Preferences will still work for the trackball. However, in order to access the additional features, you will need to download the software. It's a very easy process, just go to the website, download and install it (the instructions come in the packet). The icon will show up in your System Preferences window under the Other header. I don't know where it appears for Windows as I've only transferred the trackball between our Macs. In the trackball program, you can adjust the usual features (scroll speed, click speed, etc) and also the left/right combo click which you can set to do stuff like go back or forward. The program also allows you to choose which direction to have the scroll ring turn to go up or down. The default is set to clockwise for scrolling down.The buttons: overall, they're pretty standard in function. However, I do find that sometimes in certain programs like a Flash game, it won't always want to click on the first try, so I wouldn't recommend this for gaming purposes for games where you do need an immediate response. All other uses, I haven't really noticed any problems. I love the option of being able to set the dual click to do something :) As a first time trackball user, something else I also had to remember to do was take my fingers off the ball before clicking as I often catch myself nudging the ball when I click and then missing the spot I wanted to click. Same goes for the scroll wheel. I seem to subconsciously fiddle with that too.Trackball: No issues with it at all. It took some getting used to with adjusting from a mouse or my tablet and I found myself trying to click on the ball itself a number of times. *lol* But no fault of the device.The scroll ring: So far, I haven't experienced any of the major problems that have been complained about so far. Up till about a week ago, I hadn't gotten around to looking into the trackball's software and once I did, it made a huge world of difference with how smoothly the ring scrolled. It felt a little slow, previously to the point where it sort of staggered sometimes. I love how I can now just give the ring a quick flick with a finger and I'll be back at the top of a web page. I've actually caught myself trying to do that with a scroll wheel on a mouse at work and wondering why it just inched up instead of flying up where I wanted it! Keeping in mind of the complaints though, I have been careful with the wheel and trying not to use it when I don't feel I really need to, as not to potentially abuse it to death as I really like it. So if I'm scrolling to skim an article or search it for something, I'll use the scroll bar on the browser, which with the trackball is pretty effortless.Extras: It includes a wrist rest that you can attach to the end of the base. I didn't bother with it as my desk has a built in one.Size of whole unit: it's a decent size for me. My hand length is about 7 inches and the size of the unit allows me to perch my fingertips on the ball and comfortably roll forward to the middle joint of my fingers if I want to do one long continuous drag. I've play tested some older trackballs in stores many years ago when the majority seemed to be a lot larger, so this works fairly well.Advice: if you find yourself needing to clean your trackball, don't use Clorox wipes. It leaves a sticky residues that slows down the ball's spin. I just pulled out the ball and washed it with hand soap and water, wiped out the dust in the holder, dried off everything and stuck it back in.User troubleshooting: If you find that your hand is more tired using the trackball than a regular mouse, try adjusting your chair height. This can make a very big difference. If you have an arm rest on your chair, take advantage of it and adjust your chair height to make the rest level with your trackball.