Patented Ergonomic Mouse shape is easy to use with this model for right handed and smaller handed users including young adults and older children. See Hand Size information below. The unique shape supports your hand in a comfortable or natural handshake position that minimises forearm twist and helps prevent RSI and CTS. Evoluent VerticalMouse 4 operation is similar to an ordinary mouse and places the wrist axis at about 70 to 80 degrees from the desk platform. Helps achieve neutral arm posture and the reference posture position for mousing given in ISO 9241-5.