The vertical HANDSHAKE Mouse. Size: for smaller hands (width up to 8,75 cm, measured flat at the hand's widest point, excluding the thumb). Ergonomic: healthy arm and wrist posture. Unique: short adjustment period. Adjustable DPI: 400, 800, 1600, 3200. Unnatural postures are a risk factor for the development of wrist and lower arm problems (e.g. Karlqvist 1994, Jensen 1998, Hagberg 1994). Positioning the mouse closer to the body is less taxing for the neck and shoulders (Armstrom 1995, Cook 1998). Productivity is reduced when using trackballs and touchpads, whereas standard mice and pen tablets earn high productivity scores. 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 and therefore workload in the lower arm than with a standard mouse (Quemelo & Vieira, 2013).