The G700 Circular Soffit Ventilator (A) should be a “push” fit into a 70mm (2.75”) diameter hole drilled into the soffit board as shown.
2150mm² per Disc Vent To achieve 10,000mm2/M of free airflow the Disc Vent should be fitted at 200mm centres.
To achieve 25,000mm2/M offered airflow the Disc Vent should be fitted at 86mm staggered centres as shown