Filler Backer Rod 1-1/8" x 10" is designed to fill gaps and joints in various construction and sealing applications with precision., Ideal for use in window and door frames, expansion joints, cracks, gaps in concrete, and other areas where caulk or sealant is applied., Backer rod is compatible with various types of sealants, such as silicone, polyurethane, and latex-based sealants.