Counter Flashing is made of 28 or 26 Gauge Steel, Bonderized, Galvanized or Zincalume, 10' long. Formed metal or elastomeric sheeting secured on or into a wall, curb, pipe, rooftop unit, or other surface to cover and protect the upper edge of a base flashing and its associated fasteners. It is a strip of sheet metal in the form of an inverted "L" built into a vertical wall of masonry and bent down over the flashing to make it watertight. It is usually made of galvanized steel and directs water away from areas on the roof such as the intersection of the roof and walls. Roofers will install flashing around vents, skylights, and chimneys. For architectural, residential, and commercial roofing. ASTM A-653, ASTM A-792