Blacksmith's Rule1 fold, tempered steel rule. Converts diameters directly to circumference measurements. Riveted joint with stop when ruler is opened straight. Black filled etched graduations. Graduation(s): 1/8 in.; Length: 2 ft; Material: Steel; Measuring System: Inch; Number of Scales: 3; Thickness: 1/32 in; Type: Folding Rule; Width: 3/4 in; Weight: 0.15 lb.