I've had (and still have) plenty of USGI ones. I'm looking for an SAI polymer green one. They don't break as easy as the fiberglass ones and the paint doesn't rub off. RNGR1IIRC, handguards started out in wood, than went to FIBERGLASS;
and the colors are COFFEE ; BROWN ; DARK BROWN ; and BLACK.
You still want a green; you can buy a fake one composite or you can paint a USGI one.