"Fits between the upper and lower parts of the telescopic underfloor ventilator to accommodate a vertical step of 6 to 7 brick courses. Does not restrict airflow through the main telescopic underfloor ventilator Purpose-made accessories eliminate the need for on-site modifications Lightweight and easy to handle Durable and totally resistant to decay Satisfies all NHBC requirements Manufactured to BS EN ISO 9001 and BS EN ISO 14001 Complies with all relevant Building Regulations Meets all relevant British Standards"
"Fits between the airbrick and upper front opening of the telescopic underfloor ventilator to accommodate external walls of more than 102.5mm thickness, up to a maximum of 215mm Does not restrict airflow through the main telescopic underfloor ventilator Purpose-made accessories eliminate the need for on-site modifications Lightweight and easy to handle Durable and totally resistant to decay Satisfies all NHBC requirements Manufactured to BS EN ISO 9001 and BS EN ISO 14001 Complies with all relevant Building Regulations Meets all relevant British Standards"