Z Bar is made of 28 or 26 Gauge Galvanized or Zincalume Steel, 10' long. Banded 90°, 105° or 110°. Z Bar is used to protect the horizontal joints between sheets of siding from water infiltration. The large leg of the metal goes against the wall, leaving the seat and face covering the top edge of the siding. The seat dimension, 1 in., corresponds to the siding thickness. For architectural, residential, and commercial roofing. ASTM A-653, ASTM A-792