Length of the blade is measured from the inner edge of beam to end of blades
Squares fully hardened to Rockwell 55C
Beams and blades are ground and lapped for straightness and parallelism
Both the inside and outside of the squares have accurate right angles
Designed for precision layout and measurement work which requires high accuracy
Accuracy = .0002" + Length/50,000 (blade)
California Residents Proposition 65 WARNING: This product can potentially expose you to chemicals including Chromium, Lead and Nickel which are known to the State of California to cause cancer, birth defects or other reproductive harm.