I don't recall ever seeing a logo like that, can you open the vise grips and send us a few more pics? It looks to me like there is a change in the inside diameter part way thru the bore. The numbers on the block seem strange,No 12 is generally 3/4 of an inch but the hole does not appear to be that big. Can you tell us the bore dimensions? and Welcome to tool talk I am fairly new to the site myself and not very knowledgable on most tools but some of these guys are truly amazing when it comes to some of these unknown items.