Fowler Full Warranty 52-432-246-0 Machinist Hardened Steel Square Set, 2", 3",4",and 6" Blade Size 1 year warranty offered by Fowler High Precision Made of hardened steel, these economy squares have true right angles both inside and outside Beams and blades ground and lapped for straightness and parallelism Length of hardened blade is measured from inner edge of beam to end of blades Beam grooved at inner corner for clearance of burrs and dirt Squareness of the blade edge to the working face of the stock is  0.0006" for 2" and 3" models, and  0.0008" for 4" and 6" models