Hinge Kit Fits Square Base Size 64 in Compatible Grainger Part Number 4YY12 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 UL 705 Compatible Manufacturer Model Number GB-500 GB-540 For Use With Dayton Roof Mounted Centrifugal Downblast Ventilators Having a 64 in Square Base