DIN 975. Metric - A4 Stainless Steel. To DIN975 A4 grade 18//8 stainless steel (Type 316 S16) Higher level of corrosion resistance than A2 S/S Suitable for use in most food, medical, chemical, construction and electronic applications M3 has a thread pitch of 0.5mm M12 has a thread pitch of 1.75mm M16 has a thread pitch of 2mm