Visqueen’s GX Ultimate Top Hat Units are designed to seal around service pipe penetrations. They are available in diameters of 110mm and 160mm. The GX Ultimate Top Hats have low permeability to Hydrocarbon. They are designed to be used in conjunction with the other GX Geomembrane system products to protect against Hydrocarbons. They are made from high quality single layer HDPE with strong resistance to puncture and tear.