Depends which one you buy. Some have optical mice, some have the ball type. Buy an optical one and it will (surprise surprise!) be optical.
The wireless option seems to be fine, though it does pay to spend a bit more sometimes. Depending on how much and how you use a keyboard will affect how much you notice the difference between a good one and a poor one.
I use an optical mouse plugged in to the usb, I was reffering to an optical wirless mouse .the mouse itself that connects to the wire less sender .I know the wireless keyboards are ok .but the combination of both on one sender .does that use an optical mouse or a ball tracker mouse sorry I am so thick .
I supply quite a few Genius combination Wireless Keyboard/Optical Mouse. The nice thing is the charger is in the wireless pickup, and you get 6 batteries - 2 for each unit, and two spare to keep charged up.