M-D Gray Polyethylene Caulk Backer Rod For Gaps and Openings 20 ft. L X 3/8 in. T

The 3/8 in. x 240 in. Backer Rod is ideal for filling gaps. The backer rod is recommended for use in filling large gaps and openings to prevent drafts. The backer rod also provides a sound surface for caulking projects. Non-absorbent, closed-cell polyethylene pre-caulking material
Easily trimmed to size with scissors
Twist multiple strands of cord together for extra large gaps