This is an interesting knife. It has a few odd things about it.

It's a 1964-ish Model #16 Diver with a Low S stamp.

The sheath is a pancake style which was common on the 16, but it has a stone pouch which is not common.

It has a tenite handle, but what makes that odd is that Low S knives were usually considered past the tenite handle period.

The tenite is secured using the single screw, filled hole method, usually seen on brown and black micarta.... very unusual.

Last is the etching on the back of the blade. There is the owner's name, but also the blade has been etched as a ruler. You can see the numbers 1 thru 6 from the tip to the hilt. Of course the hilt is 7"

Joe Dorsky and I discussed it and he recalled some guys that were abalone divers using these and using the ruler to size the catch in some way.

All in all a pretty cool knife.