
1/8 inch used to remove three (3) badly rusted set screws holding a 1 1/2 hp motor shaft. to the brass impeller of the pool. Days, and then with this head, 6" extension, and 1/4" ratchet handle, they were relatively easy to remove. more pressure. The shorter hex head worked great, although I first tapped the end of the extension to fully cauterize the tool and then had to loosen the set screw with pliers after removing it.