I have had this button compass for a few years. It points in exactly the same direction as more compasses I have. I have tested it on top of mountains in Tahoe. Please note it is fluid filled.

http://www.survivalresources.com/store/product.php?productid=16186&page=1

Even though one has not failed on me, I use this type of compass as backup. I would NOT recommend trying to put this on a watch because it is a bit too thick for that. Also, you effectively turn your rugged watch into a delicate bracelet with which you must be careful.
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