It's a saddle for your hand
Review Using a mouse in the wrong way for long periods of time will gradually and unremittingly put strain on your forearm. If you are unlucky, the damage may be permanent, leaving you in constant pain. So while you chuckle away at this funny looking mouse, bear in mind that it might just prevent years of suffering and save your livelihood.
Hippus's HandshoeMouse: a design based on medical research
According to its Dutch manufacturer, Hippus, the HandshoeMouse was developed from ergonomic studies by university medical schools in Rotterdam and Maastricht. These studies show that conventional computer mice induce users to over-exert certain muscles in the hand and arm, which can cause problems all the way up to the neck. The objective, then, was to design a mouse that encouraged the hand to relax.
It may look like a maquette by Henry Moore or a toy stingray, but the HandshoeMouse is supposed to act like a saddle for your hand, requiring no active tension to control.
There is nothing symmetrical in the design. A deep ridge down one side gives your thumb somewhere to rest, rather than something to grip on. A gentler curve down the other side allows your four fingers to lie naturally and loosely together over the top of the mouse. The bulbous central part of the device supports your palm, while the extended flat area towards the back keeps your wrist off the desk top.
A relaxing hand job from Holland
This support for the wrist is important, as Hippus wants you to relearn how to use a mouse without lots of wrist action. Instead, you should allow your entire forearm to move, which, in turn, allows you to relax your shoulder. Conventional mice usage, by contrast, tends to lead most users to tighten their armpit and restrict the blood circulation -- increasingly so when under pressure.