As well as your standard left and right buttons flanking a central button and scroll wheel, two buttons also sit either side for your thumb or little finger to operate. For me at least (and presumably for the majority of people, considering the amount of research SS put into this mouse) these side buttons fall perfectly into a position just above where you grip the sides of the mouse thus making them easy to find when needed yet not easy to accidently press. Likewise the scroll wheel and the middle button are easy to reach yet don't get in the way in the heat of battle. All the buttons have a lovely light but positive action and respond instantly with no delay between pressing the outer surface and the micro switch being activated.
The scroll wheel has a fairly deep rubber finish with a fine set of lines cut into it for easy grip. It has a notched movement and is very lightweight, making for very accurate scrolling – particularly useful when selecting weapons in Counter-Strike, say. This does, however, mean that you can't flick the wheel to scroll rapidly through long documents like you can with weighted wheels as on the Microsoft SideWinder X8. This is largely made up for by how easy it is to press the scroll wheel button without jogging the wheel, though.
Below the scroll wheel sits the CPI switch which lets you change between two pre-set CPI levels - the LED above the button indicates which setting you're currently running. This may sound like a fairly limited system compared to some gaming mice but, after talking to many gamers, SS realised most people seldom use more than two CPI settings per game and more often, in fact, use just one. As such SS lets you choose exactly the setting you require for each of the two levels and you can just switch between them. Incidentally CPI is what SS uses to refer to the more common DPI (Dots Per Inch), as SS feels DPI is misleading nomenclature.
Part of the SS CPI philosophy is that you should set your Windows mouse speed setting to half way along the scale (position 6), which corresponds to a nominal level of one. Likewise you should set the mouse speed of whatever game you're playing to one. By doing both these things you avoid any software interpolation meaning that whatever CPI you set on the mouse is exactly what you get on the screen. This is why you can control the CPI level so exactly; as it's the only adjustment you should make.