Grey 9" x 3" Air Brick VentsPack of 10Plastic interlocking air brick ventilator.Clip together facility provides a choice of ventilation sizes.Can be stacked together to create 9" x 6" and 9" x 9" combinations.Additional G935 extension sleeves available in menu options.Moulded in mortar key ensures secure adhesion to the building fabric.Meets NHBC requirements for the control of condensation in buildings.Manufactured to BS 493:1995 + A1:2010.Other colours and ventilation fittings for this product available in our shop.UseAir bricks to can also used in conjunction with the telescopic underfloor ventilator for providing ventilation below suspended ground floors.Used in conjunction with cavity sleeves for ventilation through external walls to a building interior.QualitySatisfies all NHBC Standards 2008 Edition.Manufactured to BS EN ISO 9001 : 2008.Complies with all relevant Building Regulations.Meets all relevant British Standards.‘Equivalent Area’ tested by BRE to BS EN 13141-1:2004.