I found two fat little Round "O" Plombs at the Swap Meet last weekend. Tools are stamped:
Tool 1
(Front) PLOMB TOOL CO LA CALIF (CALIF is only partially readable)
(back) 7/16 S.A.E. 3/8 (3/8 is inverted)
Tool 2
(Front) PLOMB TOOL CO LA CALIF
(back) 7/16 S.A.E 3/8
AA shows one wrench of this type, but not sure of the date. I think that the round "O" and the ID with LA CALIF makes them pretty early, 20's or 30's. Am I good on the date???
I had never seen any this thick. They are around 7/16" thick.
Jim