Bought for 990r. I am satisfied with the purchase, very comfortable both in terms of the circumference of the hand, and in terms of setting the buttons, sensitivity, etc. A paid add-on is not needed at all and absolutely does not affect the operation of the mouse, hammer it, it is only necessary for schoolchildren for show-offs, who think that if they buy it, they will bend over. The mouse is worth its price. P. S. There is a sixth (!) year of use, the flight is normal! Everything works, every 1-2 years I change the Teflon footboards, since there were already 4 spare ones in the kit. In short, I wipe away tears of happiness)