I believe their were 3 different Phil Sprockets so far (correct me if I am wrong).

The first were shiny on one side and kinda funny on the other. I think those might have been plated. Never purchased or tried one.

THe second batch was blackish (like EAI) hardened steel. Used one - it was great. Con it rusted a little, but that could be wiped off easily.

The third (current) batch: Triple hardened stainless steel polished! That is the one I am using now. So far perfect. The best cog I have ever seen and used.