content: I don't know how long a track ball like this is "supposed" to last. I bought this one as a replacement for one I've had for a few years. I use my track ball all day every day and have had just about every type of mouse or track ball there is. This is very reasonably priced, comfortable and performs great on my iMac. I also have the model that is a little less expensive on my PC.I bought the second Trackman because the scroll wheel on my original one had stopped working. While I was waiting for the second one to arrive, the first started working again. I'll hold onto the other one though because I'm sure I'll wear the second one out.... someday...