After 4 years of use, the wheel began to reverse and fail. Complete disassembly and cleaning solved the problem. Also, the braid was torn closer to the junction of the mouse itself (black electrical tape helps here too, although it could have been soldered) keep using and enjoy! Different pros: Beautiful and reliable X7, comfortable key layout, high-quality assembly of the mouse itself. Laser. Cons: Fragile wire at the junction with the mouse (revision with rubber braid)