Introducing the 1201 Top Hat, a collar for sealing telescopic underfloor vent where gas protection is required. The 1201 Top Hat has been designed to work with both the 1201 and 1201XL Telescopic Underfloor Ventilators, giving you outstanding versatility and value for money. Suitable for Radon, Hydrocarbon, Methane and CO2, this top hat stands out due to its excellent protective features meaning you can be confident in its effectiveness.