See photos. I have some of the uncommon Iida latch type Guntos and have a question about their differences in design. There are subtle differences in their design and function. No knurling on one, no patent number on another, different hardware used. I was told that the one with no numbers could be a prototype or a manufacture before patents were issued. It may also be from another manufacturer as there are many subtle design differences between the two. Any help would be appreciated.