Galvalume® sheet is made to meet ASTM Specification A792. This specification covers a number of requirements, including coating weight. AZ50 and AZ55 are the English unit coating weight designations indicating that, respectively, 0.50 ounces per square foot and 0.55 ounces per square foot of the aluminum-zinc alloy coating have been applied to both sides of the Galvalume® sheet. Converting these coating weights to coating thickness, AZ50 is equivalent to about 0.8 mil (0.0008") on each side of the sheet, and AZ55 to about 1.0 mil (0.001") on each side. In metric units, AZ150 is equivalent to about 20 microns and AZ155 to about 25 microns on each side.