Blue / Black Plastic 70mm Soffit Vents Pack of 4 Plastic push in soffit vents for roof and eave ventilation. Diameter hole needed: 70mm. Meets building regulations. Made in durable polypropylene. UV Resistant material to stop sunlight fade. Insect grill- no unwanted guests. Provides a free airflow of 2150mm² per unit.Dimensions Vent size: 80mm. Drill hole size: 70mm. Vent depth: 15mm.Circular soffit vents Manthorpe’s Circular Soffit Vent can be slotted into the soffit board prior to installation for new build situations or just as easily retro-fitted into existing soffits. Standard fixing for this product is a simple push twist action into a 70mm hole drilled in the soffit board. The vent features evenly spaced slots small enough to prohibit large insects gaining access but wide enough not to be blocked by debris, paint or water droplets.Product Specification2150mm² per G700. To achieve 10,000mm²/m of free airflow the G700 should be fitted at 200mm centres. To achieve 25,000mm²/m of free airflow the G700 should be fitted at 86mm staggered centres. Push fit into 70mm diameter hole in soffit board.