Empire, 6", True Blue, Blade Pocket Combination Square, Vials Are Accurate To Within .0005'' Per Inch, Heavy Duty Machined Square Head Up, True Blue, Vial For Accuracy, 6" Steel Blade With " Graduations, Self Aligning Draw Bolt Helps With Quick Measurement Changes, Hardened Scriber For Marking Surfaces, Machined Square Head For Accuracy.