Mouse features an ergonomic design to help you rise above discomfort & reduce muscle strain, decrease wrist pressure & improve posture. Vertical construction keeps your hand in a natural handshake position to reduce muscular strain by 10 percent & promotes a more ergonomic posture. 57-degree vertical angle reduces the pressure on your wrist, while your thumb is positioned comfortably on the thumb rest. Advanced optical tracking with a dedicated cursor speed switch results in four times less hand movement to reduce muscle & hand fatigue. Its unique form is designed to fit a variety of hand shapes & sizes while the textured rubber surface assures a solid, natural grip.