Put your hand out in front of you, palm facing downward. Now, turn it to the side. Do you notice that it has a natural curve to it? It’s important to choose a mouse that properly supports this curve, just as you would look for arch support when buying a pair of shoes. Well, you may not always look for it when purchasing, but if you walked around in them all day, your lower back, legs and feet would let you know rather quickly whether they truly support you or not. Ditto for a mouse.
If, for example, an ergonomic mouse is too large for your hand, it can cause strain on the fingers as they must stretch to fully grasp it. Likewise, a mouse that is too small can increase the level of gripping needed to properly secure the mouse in place. Both scenarios are quite common and can be major contributors to undue pressure and discomfort in the forearm and wrist of the user.