Hinge Kit, Fits Square Base Size 42 in, Compatible Grainger Part Number 56MW69, 56MW70, 56MW71, Material Galvanized Steel, Includes Hardware Kit, Reinforcement Angles, Retaining Cable, For Fan Type Downblast Fans, Upblast Fans, For Fan Mounting Type Roof Mount, Container Capacity Not Applicable, Standards AMCA, NFPA 96, UL 762, For Use With Dayton Roof Mounted Centrifugal Upblast Ventilators Having a 42 in Square Base