13MA Millimeter Reading Double Square Starrett 13 squares are very popular with machinists, toolmakers, and patternmakers. The sliding blades are adjustable making it practical for a wide variety of uses. The faces of the head are ground square. 100mm with Graduated Blade square. FEATURES With Graduated Blade Only mm Grads Both Edges One Side; mm and 1/2mm Reverse Side Double Square with hardened blade 100mm SPECIFICATIONS Type: Double Square with hardened blade Blade Length (mm): 100mm Graduations: mm - 1/2mm Material: Steel Includes: With Graduated Blade Only