Some mice are big and expensive, some have numerous buttons and functions, some have trailing wires, but the Microsoft Wireless Mobile Mouse 1850 is none of those things.
This is a compact and lightweight model that is small enough to travel with or to keep on your desktop next to your computer - it supports both Windows PCs and Apple Macs. It is also symmetrical and so it can be used by left or right handers.
This device is battery-powered and uses 2.4GHz wireless technology, communicating with the computer using a mini transceiver plugged into a USB port. Apparently the tiny transceiver can be stowed away inside the mouse when you are travelling so it won't get lost. That's a useful feature.
The price of this mini mouse is a very reasonable $14.95 and you can get more information here.