This innovative R-GO HE Break Ergonomic Mouse features software that uses colour signals in green, orange and red to let you know when you should take a short break. During mouse usage the light changes colour like a traffice light. This helps to improve comfort and prevent muscle strain. The vertical shape is designed to help improve circulation and relieve muscle tension, with a more natural and relaxed hand position. This medium, right handed mouse is designed for hands measuring 165 - 185mm.