From what began to strain a week later - involuntary operation of the right mouse button. Stupidly under the weight of a finger sometimes works, at the most inopportune moment. Too easy to move with minimal resistance. Maybe the specifics of my copy, but the previous mouse, both keys were tighter in pressing. Addition: after a couple of months, the side keys began to work at the same time if you press any of them. I took it to the store - they returned the money. In general, I do not advise - the reliability is low.