The design is similiar to the anti-sag meters with an extended gap range of 1 to 18 mils (25.4 - 457.2 microns). The 6 mil (152.4 microns) gap section is extended relative to the other gaps.
When a drawdown is made, a series of parallel stripes of different wet film thickness will be formed. This panel is placed on a vertical surface with the stripes horizontal and the thickest stripe lowest. As the film stripes sag downward, some of the uncoated 1/16 inch (1.6 mm) spaces may become entirely covered. The clearance of the gap that produces the thickest film stripe, not sagging completely to the stripe below, is the anti-sag index of the coating.