CRL Locking Strips for Two-Piece Self-Sealing Weatherstrips are offered to complete the system when working with Two-Piece Weatherstrips. Designed to give you the strongest and tightest fit when used with CRL's Two-Piece Weatherstrips. This weatherstrip is made of Ethylene Propylene Diener Monomer (EPDM) Material. This tool can be used to make your installation easier: CP772095.