Starrett Master Precision Square Blade

The Starrett Master Precision Square (Series 20) is a hardened tool steel precision-checking square. Machinists, toolmakers, and inspectors use it as an engineer's square to check squareness when extreme accuracy is required. It is a non-graduated square, so it is a checking tool and not a measuring rule.

Key Features:

• Extreme accuracy: squareness accuracy to .0001" (0.0025mm) every 6" (150mm)
• Hardened, ground and lapped: beams and blades are finished this way to ensure parallelism and straightness
• Quality construction: made of high quality tool steel
• Relief groove: the beam is grooved at the inner corner to give clearance for burrs or dirt, so the blade seats squarely against the workpiece
• Non-graduated design: built for checking squareness

Starrett has been making precision tools, gages, and measuring instruments since 1880. The Master Precision Square is made to hold its accuracy over years of use in the tool room, inspection lab, and machine shop.