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