Track Roller System of Measurement Metric Shaft Diameter 30 mm Shaft Material Alloy Steel Shaft Material Grade 52100 Shaft Type Concentric Drive Type Hex Socket Drive Location Stud Shaft Thread Size M30 x 3.5 Shaft Thread Length 31 mm Head Diameter 57.2 mm Head Length 22 mm Hex Drive Size 12.2 mm Overall Length 135 mm Standards AS 9100 ISO 9001