Kensington Expert Wireless Trackball Mouse (K72359WW) Black, 3.5" x 6.1" x 8"

I have tried them all, and this one is the best. Is it perfect? Is it for everyone? No.The big advantage this unit has over the others has been overlooked by other reviewers. When I use this track ball, there are many hand positions that work well. Quite often I drape my hand over the whole thing and move the ball with the callouses of my pointing and ring fingers that are on the palm of my hand. I can rest my hand on the table and use a fingertip or two. One of those that I like the best is cradling the top of the ball in the nook of my #1 and 2 fingers, just under the knuckles halfway back on the fingers.I use five or six different positions, and they are all comfortable and easy to be accurate with. The large diameter ball makes this possible, along with places on the housing that aren't buttons that fingers can rest on. I also put some of my hand weight on the ball. By using many different combinations of positions, the chances of injury is as low as it is going to get. I never get sore from the track ball, and I have been computing for a long time (please don't ask).The scroll ring is also easily turned with a finger or two, or thumb. From the top or either side. It's way better than those thumbwheels. The ring to has a clicky feel when turned. It's made that way. If you don't like it you can take it apart and remove the magnet. The screws are under the feet, which are just stuck on, and there are a couple more under the ball.Sometimes the ball is sticky out of the box. For a track ball to work, the friction of the ball has to be very low. This high friction goes away after a while, but you can't wash it away with soap and water for some reason. Another reviewer suggested greasing and polishing and I expect this works. Perhaps a solvent wash with alcohol. Maybe the oil from your skin gets in the plastic and lubricates it. If I give mine a spin right now it will go for 3 revolutions.I have large hands, and this thing is perfect for me. If you have small hands it may not be for you. I threw the wrist rest away. It's useless. I often put the track ball on the arm of an easy chair, and my whole arm and hand are supported perfectly.Setting it up for your own tastes with the software is important. It makes a huge difference. I use my computer mostly for programming and browsing, with some photoshop thrown in. Although I have a tablet, I can actually do better with the track ball in most cases when I use photoshop to fix pictures. For browsing, I have one of the upper buttons programmed to be the browser back button. That and the scroll ring will spoil you big time. Fair warning.The one thing I would like is to be able to adjust how much pressure it takes to trip the buttons. I sometimes screw up and inadvertently hit the upper left button (back) when I don't want to. I can see Kensington rolling their eyes - it's always something...I tried their new track ball, the slimblade, and it wasn't quite as good. The case and buttons were one and the same, so finding a place to rest hand and fingers resulted in a lot of unwanted button presses. Also, the buttons take different pressures depending on where you hit them. This unit doesn't behave that way. The buttons take the same pressure no matter where they are pressed. The rotating ball vs scroll ring was a non-issue. I went back to this unit because it's more ergonomic, even though it's a lot thicker.I am about to buy my fourth one of these. I have managed to break several in different ways, through no fault of the manufacturer. In general these are pretty tough units. I have dropped mine off the chair arm many times and it has been ok. The cord is not tough enough to withstand a battle with the vacuum. The unit works well with a 10 foot usb passive extension cable (even though it's too long for spec). I can tell you that if you put it on the floor, and the dog steps on the ball, one of the bearing holders is likely to break off...

I have written a complete review of this device in its Wireless Version which is no longer manufactured. Its overall design has been well described in these numerous reviews. I would like to address a few of the complaints registered in some of the reviews on this thread, at least IMHO:1) The bearings on which the ball rests are different, and overall, there is no significant change in build quality which is more than adequate.2) Initially I also had some difficulty on Win7/64 with Trackball Works 1.04 and 1.01, the European version which tech support recommends when you call in to complain about the former. In my case, this represented some sort of software conflict which was no longer the case when I gave it another try after having had to reformat and reinstall my system for other reasons. Initially, although I could program the trackball without difficulty, it would intermittently hang, or my computer would crash. Since the reinstall, now for about 3 months use, Version 1.04 works absolutely fine with this Expert Mouse, but install the software before connecting the device, as mentioned. Absolutely NONE of the initial problems have recurred. Trackball Works has some problems with complete programming of the Slimblade Trackball version and Kensington is working on it, with a supposed upgrade to the software due in March, at least at the time of this writing.3) The ergonomic issues raised by some of the reviewers are legitimate, but it depends a great deal on the individual user. I agree that the "wrist rest" supplied is not a very successful solution. Some will prefer the flatter format of the Slimblade, but I don't think the four buttons work as smoothly as those on the Expert, and are very dependent on where you place your fingers on them, which is not the case with the latter which are nicely designed. At work, I use this trackball for hours on end, now for years, in our radiology department, scrolling through images, and have had absolutely no wrist or finger pain. One of the tricks is to operate the mouse with your hand canted to the right at about a 30 degree angle which helps to obviate more extreme wrist extension. Give your hand and wrist a brief rest by changing position every few minutes which can easily be done automatically during the workflow since you aren't gripping something. Any pointing device without rest will be a nuisance. For those who are particularly sensitive, place a small bean bag place under the palm of the hand, not the wrist. Since you aren't spatially moving the unit, it is not intrusive, if you buy a proper sized bag.4) Complaints about the scroll ring, IMHO, are entirely unjustified. It works very well. I have had no problems with its function on this unit, my previous wireless mouse, or any in our Department at work.5) Complaints about the ball's being sticky and insensitive are also groundless, IMHO. You will find slight "newness", reflected in slight stiffness,when you first use the unit. This will clear promptly, and even more quickly if you just spin the ball for a couple of minutes with moderate downward pressure to break in the interface between the support pins and the ball. Periodically clean the ball with a little soap and water, then alcohol to restore a smooth surface, and repeat the conditioning routine, in an abbreviated form. At the same time, inspect the pins on which the ball rests for accummulated dust and debris, and make sure they're absolutely clean. Works like a charm.For those that don't like the scroll wheel, try the Slimblade where scrolling is done via the ball itself, turned transversely. That works well....it's just a matter of personal preference. I personally prefer the larger ball on the Expert versus the Slimblade, and the independent scroll wheel. The interface cable on the Slimblade is a little more robust and less prone to kinking if you move the trackball around quite a bit, for example, if you're also using a graphics tablet on which you seat the trackball. In any case, I don't think it's an issue, particularly if you take a bit a care of how you set the mouse down so that it isn't repetitively stressed with a kink. BTW, I couldn't find the magnet that one reviewer talked about at the bottom of the receiver for the ball. All that's there is the optical pickup. BTW, if you use the Intuous 4 Wacom tablet, the RF mouse they supply is greatly improved over previously, and is nicely programmable, except for no control over acceleration which some users may find a distinct negative.Bottom line: HIGHLY recommended after years of experience using this trackball. Works perfectly well with Win 7/64.