25-1/2"ID Square Severe Duty

Severe Duty Roof Curb, Fixed, Non Ventilating, 12 Gauge Steel, Height: 24", Curb Square (OD): 29", Curb Square (ID): 25-1/2", Use with Dayton Ventilators: 1DYK6, 1DYK7, 1DYL1 And 1DYL2, Weight:
121Lbs, Origin: USA