This mouse has a grooved metal scroll wheel that operates quietly and has well-defined steps in its default, notched scrolling mode. You can press the button directly behind the scroll wheel to manually toggle between a precise, line-by-line notched scrolling mode or a faster free-scrolling mode.
Additionally, holding down either side button and scrolling up or down scrolls horizontally instead of vertically.
In the configuration software, you can also adjust the Scrolling Force and turn on or off what Logitech calls Smart Shift, a feature that automatically toggles between the notched scrolling mode to the free-scrolling mode when you begin to scroll more quickly.
