Glass Filled PTFE (known as fibreglass reinforced PTFE) is manufactured from a base of virgin PTFE which is strengthened by the addition of glas fiber. This material exhibits less deformation under loads at both high and low temperatures which increases its utility as a sealing medium. The addition of glass also improves the wear and friction behaviour of the PTFE sheet Gass filler offers better creep and wear resistance, improves dimensional stability, raises the heat deflection temperature, improves creep resistance, and improves electrical insultative properties.