But also for presentations can be the M570 good use, since they may well disappear in a (wide) pants or jacket pocket. The trackball works perfectly in every situation. The range between the receipient and trackball is about 15 meters. Who wants to be a half-crazed unloved work colleagues just plug the tiny receiver in the PC and move the ball from time to time ....: D
What do I have to complain about is that it is only as the M570 cordless and is not really suitable for people with large hands.