Navy Magazine Why?
 

Why, When and Where!! I always believed the concentric ring were for better grip in naval situations. Lately in photographs I've seen even harsher conditions in muddy trench warfare artillerys seem to need it even more than their naval cousins. They are of course interchangeable. I note the Swiss have their own style that never seems to gets dirty and have never seen war and always seem safe in the alps and content with their chocolate and gold! Eric

All observations are true enough; I believe the guy that made the first one just had a little extra time that day.