[G.M.]

These are OK for steel heads but I never needed one for steel heads. On aluminum heads if they are really stuck these will break more heads then they will remove. The only way I found to remove tight aluminum heads is with a thin wall core type drill. This has a thin wall, the ID is slightly larger than the stud and the OD removes very little from the stud hole in the head. This material between the stud and head is what locks the head on. Removeing the studs also works but breaking them off creates larger problems. G,M,