Instruct: Classify a given review as either positive or negative.
Query: Track ball is huge - I'll call it my "dead rat"

Great to use, this is my third one in twenty years - they are all still working like the day they were new. I'm so used to using a trackball that I have to retrain myself when I encounter one of those little mice. The best thing is that the cursor doesn't move when you let go of the ball - mice tend to creep a bit when you nudge the left and right ears (buttons). With a trackball, everything stays-put. I call them a 'dead rat' 'cause they are like a giant mouse that has gone belly-up. Great tool for all applications, especially CAD. I don't leave home without it - really - I put in my bag with my laptop and go. No trouble with TSA, they just smile.