ANVINKU 400 Pieces Lock Washers 7 Sizes Locking Washers Inner Tooth, Manganese Steel Clamping Discs, M3/M4/M5/M6/M8/M10/M12 Washers. Size: M3/M4/M5/M6/M8/M10/M12. Durable and secure locking - Made of high-quality manganese steel, these locking discs provide excellent grip and high vibration resistance, so that the bolts stay in place.
eBay