Late '6o's professional that is getting harder and harder to find. Sailboat casebackGood bezel that has been lightly polished and touched up. Rarely seen big crown, screw down. Non quickset date, serviced within the last year. Mounted on a lengthy beads of rice bracelet that fits my 7-1/2" wrist with the dive extension fully closed. Clasp is Expandro, but later model unsigned. Dial is original,spider webbed and doesn't appear to be re-lumed.Tons of references worldwide.Beautiful example