This one is another mystery to me because I can't find another like it on eBay and or Google. By the way it was made I am thinking 1920's. No marks. Came from a house that also had very early 1920's wrenches and tools up to 1950's. Looks like he also was a brake mechanic. Lots of brake tools. No other one like it in any size at house.
Here is what I know. 1/2" x 9/16" open end. 17" long x 3/16" thick. Handle consistently 19/32" wide. Weighs 10 oz. exactly,