MS 20/12 Steel grade 4.6 zinc plated MS 20/12A2-70 stainless steel MS 20/12A4-70 stainless steel MS 28/15 Steel grade 4.6 zinc plated MS 28/15 A2-70 stainless steel MS 28/15 A4-70 stainless steel MS 38/17 Steel grade 4.6 zinc plated MS 38/17 A2-70 stainless steel MS 38/17 A4-70 stainless steel