Metric swivel hoist ring. Top washer has the following features: The working load limit and recommended torque value are permanently stamped into each washer. Washer is color coded for easy identification: Silver metric thread. Individually proof tested to 2-1/2 times working load limit. Bolt specification is a grade 12.9 alloy socket head cap screw to din 912. All threads listed are metric (ASME/ANSI B18.3.1m). Designed to be used with ferrous work piece only. Bolt size identification: The size of the bolt will be stated as in the drawing below.