Hinge #1, standard 11 gauge, plain steel. Goes between section 1 and section 2 on the door. The #1 has the smallest offset of the numbered hinges because the bottom part of the door stays closer to vertical as it moves. Replace it if the hinge is bent, cracked, or the holes are worn out. Check the number stamped on your old hinge to make sure it is a #1 before ordering. The 11 gauge steel is thicker and stronger than lighter standard residential hinges, so it works well on doors that see regular use.