This 4" double square is accurate and adjustable. It is the perfect small-size tools for checking or setting 90 degree angles. Graduated rules are of hardened steel with precision-machined stocks. Starrett tools feature unerring American-made precision and durability. Their century-old dedication to producing only the highest quality tools has earned them the well-deserved title of "the world's greatest toolmakers". Measuring tools have working surfaces ground to a demanding +/- .00001". Rules are made of engraved, hardened, premium-quality steel. This is the tool professionals rely on for accuracy.

• Perfect small-size tools for checking or setting 90 degree angles
• 4" double square, accurate and adjustable
• Measuring tools have working surfaces ground to a demanding +/- .00001"
• All rules are marked with 1/64", 1/32", 1/16", and 1/8" graduations