BS8485 compliant Top Hats are designed to provide a highly effective seal around service pipes in a gas membrane system. Where service pipework needs to penetrate a gas barrier membrane, you need to use these pre-formed  Top Hats to create a gas-tight seal. 
SIGMA GPS Top Hats have been manufactured from polymers that protect properties and occupants from harmful ground gases.
 
Each Top Hat comes supplied with 1x Jubilee Clip per unit.