I was at a swap meet last weekend, at Baraboo, Wisconsin. I found a pair of pliers of this type, but with a different name on them, and got them for $3. They were missing the spring that tensions the lock/release tab, and had a dot of weld spatter, but were otherwise decent. Later, I came across another pair, this time with the Sta/Tite name & logo, also patent pending like those in this thread. [I
thought] I took a photo of the Stat/Tites, which were marked $45, but discovered that I'd used up my external memory on a digital camera, so don't have it. Here is a photo of mine, with a quick-&-dirty replacement spring. Side-by-side, the two pliers appeared identical in tooling. However, mine are stamped "JAPAN" on one handle, and laser-marked "GIBBSVILLE CHEESE CO. Bob & Lee Van Tatenhove" on the other.
The latching system seems to permit a very tight grip, though not like Vise-Grips (tm) with their toggle-locking action, of course. The release tab works easily and positively. The spring can be lost while changing pivot points (they're slip-joint in that regard), but otherwise, they seem to be very well designed and made.
The Gibbsville Cheese Company exists: see
http://gibbsvillecheese.com/about-gibbsville-cheese/. I'll try to find out the story behind these custom pliers.