1203 – Horizontal Front Extension Sleeve
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

1206 – Horizontal Rear Extension Sleeve
Fits into the lower rear opening of the telescopic underfloor ventilator to accommodate cavity widths between 50-150mm – or internal walls of more than 100mm thickness, up to a maximum of 200mm