(M6x10 6pcs, M6x12 6pcs, M6x16 6pcs, M6x18 6pcs,M6x20 6pcs). ???? Quality 304 Stainless Steel ------ Endurance and Rust-Resistant: Made of high-quality 304 stainless steel, our battery bolts and nuts are built to last, with excellent resistance to rust, corrosion, and oxidation.