I bought a pretty sweet kit of many M6 bolts with 8mm flange hex heads. Various lengths. The kind common on bikes that's hard to buy at a regular nut and bolt supplier. I haven't been able to find what coating is on these bolts, if any, other than they're 8.8 steel. They're silver, polished, and to my eye there's a slightly blue silver. Zinc? It's one of these Tusk Racing kits.