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