Shape: the shape of an ordinary or generic computer mouse that does not correctly fit the user's hand, requires the user to grip and hold, which over an extended period will cause tendon and muscle fatigue in the hand, wrist and even the elbow and arm.
Overall size: the size of the computer mouse does not properly fit the size of the individual's hand. This means there is not enough support for the hand, having optimal support and comfort is required to minimize fatigue with computer mouse operations. Individuals with smaller hands should use smaller mice. On the contrary, individuals with larger hands should use larger mice.
Right and left hand compatibility - the computer mouse is not compatible with the user's dominant hand. The computer mouse should be compatible with the dominant hand of the computer user, left-handed computer mouse users should use an ergonomic computer mouse designed for the left hand.
Wrist Position: An ordinary, generic horizontal computer mouse requires your forearm to twist away from its natural position, this causes more strain on your carpal tunnel, wrist tendons and ligaments.