70mm Circular Soffit Vent by Manthorpe are ideal for both new builds and for the replacement of existing soffit vents. Ideal to prohibit the entrance of large insects and wide enough not to be blocked by debris, paint or water droplets. Push fit into a 70mm diameter hole in soffit board Suitable for installation before or after the installation of soffit boards. To achieve 10,000mm2 of free airflow these should be fitted at 200mm centres To achieve 25,000mm2 of free airflow these should be fitted at 86mm staggered centres Please also see the 76mm soffit vents available in White & Brown.