http://www.cammenga.com

I just purchased two of these for myself. They are made in two versions. Tritrium and Phosphorescent. Mine are the latter. First impressions are favourable. Well constructed like all Cammenga products. The compass is about 1" across by half that deep. It is supplied with a nylon wrist band that seem to be reasonably stout. It is a dry compass. Settles to Magnetic North very quickly with no muss or fuss. Hunting is minimal, unlike some of the poor imitations that we have all come to know and detest. Being a dry compass there are none of the problems with leakage, bubbling etc associated with liquid filled compasses. It is easy to see why this item, which has been around in it's present form for some years now, is supplied to the U.S. Air Force. As a back up item for someone venturing into the great outdoors, this is worth considering. In fact I would go so far as to say that any light plane Pilot who takes off without one of these on his wrist is not being as smart as he could be.
Yes, I know that you should stay with the plane (before the regulars have a pop at me....) but sometimes you do have to move.
Cammenga is, as you may or may not know, the sole supplier of compasses to the U.S. Armed Forces. Which is a major recommendation in itself to anyone in the market for a decent compass.
Usual disclaimer: I paid for these products and have no association with Cammenga. All products and equipment that I post about are reviewed honestly. If it's good, I will say so. If it ain't. I will tell you to avoid it.

I think that the wrist strap is good because it takes up little space & once the compass is on your wrist, the chance of losing it decreases.