I was just going to post how the set I bought has been sitting unused for almost 35 years, but finally came in useful last night to remove the completely stripped Roberts screws holding the rubber bumpers onto my tire changer. At first I though they were Philips heads and used a chisel to try reforming the cross, but one of them was worn right down with only a pinhole, so I used the one side to open up the hole, and the spiral side to SLOWLY back it out. Worked great, and no wear on the tool like your pic, but not a lot of torque or rust holding it in like a brake rotor retainer.