I finally bought them after considering steel toe caps, aluminum toe caps and various other plastic brands. Apparently not all are the same. Some of the plastic types are very cheap and the threads are bad. I've preferred aluminum and other types of metal in the past, but I've been put off by corrosion (as well as its higher cost, especially if someone decides to steal a pair). I'm glad I read the reviews and bought this brand. The value is good; they are well made; The carving is done as it should be. Basically these are really good replacement valve covers.