This CRL Pile Weatherstrip is installed by simply sliding it into the pile channel of the existing U.S. Aluminum Vanguard Security Astragal frame. The polypropylene black fiber pile resists corrosion, and has exceptional resistance to abrasion. It is silicone treated to repel water, and stabilized against ultraviolet and ozone. The backing strip is polypropylene and lasts longer than plastic weatherseals.