ArmourStick HD-Base is a self-adhering, high-performance base sheet constructed of a sturdy, nonwoven, reinforced composite mat strengthened with select glass fiber strands and coated with SBS polymers and premium asphalt. ArmourStick HD-Base offers a 3.5 inch side lap, allowing immediate sealing of the membrane along the side laps. A split release film covers the top surface of the base sheet, which is removed during installation to reveal a primerless surface for the ArmourStick HD-Cap sheet to be installed.