I bought this set after a bolt extractor set failed to remove a rounded oil drain plug. After drilling a hole in the drain plug the screw extractor was easily screwed into the center of the drain plug. My only complaint is that there is nothing included to use to screw in the extractor. However the extractor bit into the drain plug superbly and after rigging a tool to turn the extractor it easily broke the drain plug free. I highly recommend this tool.
This is a great set of tools to have if you are looking to create work. I have broken all but one of these trying to remove stuck bolts. They are made of extremely brittle steel. More like pretzel sticks than tools. The big problem comes in after the extractor breaks off in the bolt you are trying to remove. Now you have hardened steel to remove. They are junk. Of course they are made in China, where all the **** comes from. Buy American (you get that Sears..Sell American)
Case was very cheesy... No carbide cutting tips, and steel looked to be of a cheap grade. And after using, just what I predicted, the extractor Bit snapped like a twig! I guess you truly get what you pay for!