Based on this product's specifications, here are some alternatives and similar models
Hex nut Koelner M12 A2 stainless steel DIN 934 — pack of 13
Summary description:
Koelner hex nut M12 A2 conforms to DIN 934. Manufactured from A2 stainless steel, this M12 threaded nut provides corrosion resistance for fastening applications. Supplied as a set of 13 pieces, it is suitable for general mechanical assemblies, construction, plumbing fittings and outdoor installations where stainless hardware is required.