This tool did NOT work on a Mazda Miata NA cylinder head, despite online sources showing that a similar tool works well. There were two problems: the magnets do not seem to be strong enough to actually grab the valve keepers once the spring is compressed, and it is difficult to keep the tool centered inside the delicate lifter bore without scratching the aluminum walls when striking it. We resorted to using a deep socket with some strong magnets inside, which is what this tool is supposed to act like but better. If I ever want to recover my wasted money, I may try to disassemble the retaining ring and add better magnets, but it looks like it will be a hassle. 2 stars because it's solid and well-machined. Just wish it worked.
Rating: [2 of 5 Stars!]