Waltham wrist compasses
It has an OD green cloth strap. They are not really rare, but do usually fetch a nice price in auctions. I guess that's because they are such nice gadgets. The ones I have seen for sale with their orignal carboard box are all Navy issue. The one in the picture below has the following marking on the back: R-88-C-89O.
Or lookout for these:
Compass, Wrist (Waltham)
During the Vietnam War yet another variation of the wrist compass was procured and issued. The one-piece band was made of OD nylon, not cotton or leather as in the older models, with blackened brass buckle. The 1 1/8 inch case was brass, painted olive drab. The letters "W.C.Co." appear on the face of the compass, the initials of Waltham Clock Company, the manufacturer. The compass points and needle are painted with luminous paint for night visibility. The case is filled with air, not liquid, and it was not waterproof. This model was ordered from Waltham in 1968 and a few thousand of these were issued late in the war. They were not satisfactory for use in the wet, damp Vietnam climate.