From the manufacturer

Slim, Light And Ready To Travel
Ultra-slim and lightweight, Surface Arc Mouse goes anywhere without the weight or bulk of traditional mice. What’s more, you can snap it flat and easily slip it in your back pocket or bag for travel. The Surface Arc Mouse connects wirelessly to your Surface device via Bluetooth.

Beautifully Crafted
Surface Arc Mouse features a slim, smooth, unobtrusive design that’s easy on the eyes and fits beautifully within your workspace. From scroll plane to tail, the Arc Mouse is soft to the touch and meticulously crafted to sit comfortably in your hand. Choose from 3 rich colors to complement your Surface device and your personal style.