Hinge #3, standard 11 gauge, plain steel. Used between sections 3 and 4 on the door. The #3 has a larger offset than the #1 and #2 so the roller lines up properly as the door moves through the curve and into the horizontal track. If your old hinge is bent, cracked, or worn out, replace it and match the number stamped on the original hinge. The 11 gauge steel is thicker and stronger than lighter residential hinges, so it holds up better on heavier doors and doors that get regular use.