Featuring overall size of 4.0 x 4.0 in., T-45 ANSI/ISEA Z87.1.2015 Test Resolution Standard is based on ANSI/ISEA Z87.1.2015 Standard, American National Standard for Occupational and Educational Personal Eye and Face Protection Devices. Chart consists of 24 Sunburst Lines, 2 inner circles with continuous centered crosshair lines, and 1 set of vertical and horizontal 20 and 40 cycle/mm Ronchi gratings.