While keyed and combination cam locks for entry ways with rotating arms for Companionway doors are popular none under a $100 wholesale cost are made of all stainless steel. In spite of claims otherwise the internal lock mechanism is made out of steel and zinc. It turns out that only the trim ring outside maybe stainless steel. Usually the stainless steel is nonmagnetic for the 300 series metal. So put a magnet to the rotating arm to prove it. The only keyed entry way made from stainless steel is a hasp from Seadog provided by CruisingConcepts.com on their companionway doors.
Don’t get me wrong I will sell you what you want but honestly that little rotating arm’s bending moment requires so little effort that I am ashamed to try to make any claim of robustness. My door construction is the the best and very stout. To complement it with a lock that is a little bit better is so easy and it takes a key all from Seadog Line.