I believe the Dia Compe brakes that had no additional markings were just their basic model. Some of mine are "Schwinn Approved" which are unmarked and of unknown age. I have one on my single speed bike, it works just fine. I also have a "G" in my bin, doesn't seem to be materially different, but the aluminum seems to be more brightly polished. I did notice that there's a washer between the brake arms on both brakes, but mine are so old that I can't vouch for them having the original or correct parts any more. Some mixing and matching of parts may have occurred! On one brake the washer is thin metal, on another, nylon. I can see daylight between the brake arms on all of the sidepulls in my fleet.