25,000mm2/m airflow Narrow grill to block out insects The G825 Continuous Soffit Ventilator is designed to provide a solution to roof ventilation where a traditional soffit board is specified and 25mm of air flow is required. The UPVC strip is screwed on to the fascia and securely supports the soffit board which slots into the self-retaining mouth. Airflow is guaranteed through a series of evenly spaced slots, narrow enough to keep out large insects but large enough to prevent the vent from becoming blocked.