Reynolds produced 531 tapered fork blades in both "taper gauge" and plain gauge versions as shown in the catalog pages below. Taper gauge was 18 gauge (1.2mm) at the crown, tapering to 20 gauge (0.9mm) at the dropout tip. The plain gauge blades were either 17 gauge (1.35mm) or 18 gauge (1.2mm) from the crown to the tip. Gauges are Imperial Gauge.