The Goldtouch Semi-Vertical Mouse was created with an optimal slope of 66 degrees for the user who wants a mouse that is midway between a traditional ergonomic mouse and vertical mouse. Unlike vertical mice, you''ll have the power of gravity on your side when it comes to clicking, so you won''t have to use as much movement between the thumb and fingers (which in turn can require more pinching of your muscles and nerves). Sizing: Users with hands up to 7.5" can comfortably use this mouse. If the attachment flange accessory is added, users with hands up to 8" can comfortably use this mouse. Ideal Slope: 66 degree slope creates optimal comfort and hand/wrist positioning. Flange Accessory: Detachable Ergo-grip flange keeps palm off the surface of the desk. Comfortable Feel: Anti-slip texture grip and rubberized coating provide maximum comfort. Forward/Back Keys: Page forward or Page back with convenient thumb keys. Adjustable Weights: Four detachable 5g block weights for customized weighting. Plug & Play: Wireless USB 2.4 Ghz receiver allows for quick set up. The revolutionary Goldtouch Semi-Vertical Mouse empowers users to enjoy maximum ergonomic comfort with precise accuracy.