The shackle will carry its diameter in mm and a grade stamp, for instance, 10mm and be graded S, and, say, a 6mm will be graded M, and have a lesser WLL than the S grade. The shackle's pin (sometimes painted yellow) must have a greater diameter than the bow, or D section. Stainless steel is not recommended for shackle construction. It is quoted in most interpretations of the official policy that since the loading on these shackles is different when used to attach a safety chain to a road vehicle, as compared to when used in a lifting application, a road trailer may be towed that is heavier than the shackle's WLL.