Most have been clear acrylic. There were a small number made in matte frosted clear and sent to dealers in the early-mid 2000s. It seemed most of these dealers were in California. There have been a few with a chrome-like coating for Oakley photoshoots. There are fake Spike heads out there. I am not sure of the actual material used (seemed like resin) but all of the ones I have seen have been painted with artwork.....I have not seen a fake clear of frosted Spike Head (yet). However complicating things is some using real Spike Bobs and customizing it with black or white paint. So these are real ones but customized.