The HANDSHAKE Mouse is a mouse with a vertical grip. It has two buttons and a scroll wheel. Using this mouse correctly reduces muscle tension. The SRM Mouse is designed for small and medium-sized hands (hand widths up to 9 cm, excluding the thumb). The Evoluent mouse is better for larger hands. The HANDSHAKE Mouse has a powerful laser sensor and the option to choose between 400/1600/3200 DPI. - Size: for smaller hands (width up to 7.5 cm, measured flat at the hand's widest point, excluding the thumb). - Ergonomic: proper arm and wrist posture. - Unique: short adjustment period Thanks to the "handshake" position when using a vertical mouse the wrist doesn't bend sideways too much and the lower arm needs less inward rotation (Schmid et al., 2015). There is less muscle activity in the lower arm than when using a standard mouse (Quemelo & Vieira, 2013).