I'm pretty they sure they are for removing the early aluminum 21 stud heads. I looked in some KRW and Manzel tool catalogs I have and didn't see them in there so they might be from another tool manufacturer. I remember seeing an ad for that tool with a photo in one of my 1930s early automobile trade magazines. At the time I was trying to pull some Offenhauser heads off of a 59A without breaking them. I never did get them off. They were soaked for months in penetrating oil. I even tried a porta power between the lifter valley in the block and the heads and let it sit there with a just little pressure for days and they did not pop loose. It was just a spare engine I bought to get the 3-carb intake and carbs. I have so many engines I just stuck it back in the pile. I spray those studs every once in a awhile, they have been soaking for years. Eventually I might try welding the nuts to the studs and see if I can get the studs out with the heads still on and then take the heads off. More than likely, if they have that much electrolysis between the metal studs and aluminum heads they are probably junk anyway. When I saw the ad, I remember thinking about how those aluminum heads were already stuck on there when the engines were only a couple of years old. At the time there was a pair of those pullers for sale on eBay and I didn't buy them because the later heads are shaped differently along the sides and there is nothing for the tool to pull from.