This 3M/Anir vertical mouse is the only vertical product which has an scientific acklowledged documented ergonomic effect. It is preventive against CTS/RSI and it does significantly reduce the pain for people suffering from neck, shoulder, forearm and wrist/hand problems. It does not introduce other and new problems when used in a right posture. Effects are documented in university tests. All reports are available. There are 2 sizes available in black for optimal fit for the hand width. Available in wired and wireless, small/mediumand large.