Roof Ventilator Base Adapter, Function Adapts 22-1/8 in Round Base to 24 in Square Base, Material Steel, Overall Width 24 in, For Round Base Diameter 22 1/8 in, Flange Height 1 3/4 in, Compatible Grainger Part Number 4HZ50, 4HZ51, 4HZ54, 4HZ55, 5DVL9, 5DVN0, Finish Galvanized, For Fan Type Upblast Fans, Includes (6) Bolts, (6) Nuts, Metal Material Thickness 1.7 in