I had a broken stainless steel propeller in the transom of my boat. Using the smallest drill bit in this kit along with cutting fluid and a good, sturdy drill/hand, I was finally able to drill a hole deep enough to use the extractor successfully. Drilling stainless steel is difficult and time consuming, but will not burn and/or dull the drill bit. Using pullers/screwdrivers isn't for everyone, it's easy to apply crooked pressure and break them in the hole. With larger parts it's easier to weld on an extra screw, but I didn't have that option as I was working with a small fiberglass/wood screw. However, for what they are I found them to be of good quality.