I haven't been able to confirm what they are made out of. They were on the quad when i got it. I did find out they are 1990's ITP spacers but the rep couldn't tell me what they were made out of. They worked on my '89 for over 10 years my bro-in law had it and he beat the sh*t out of it. Hence the cracks, I would of used them myself but got a hold of a extended axle so... lets see some pics and ride report too.