I was looking for a replacement for my X5 Microsoft, and this approach is a lot! As now used (and fan!) BUTTONS vertical side, impossible to find in similar mouse ergonomics. The Leviathan really very similar to the X5 / X8, but slightly smaller, so I recommend to large paws. When the weight is perfect to him, a very heavy mouse you like them. To see the long term now, but for the price, it's almost a faultless.