M-D Building Products Gray Foam Backer Rod for Gaps and JointsThe M D Backer Rod provides a base for caulking to prevent caulk waste in deeper, larger gaps or joints. Backer rod can also fill gaps to protect the home against drafts, moisture, dust and insects. Can be used in both indoor and outdoor applications. Before installation, cut to desired length by using scissors. Foam gap filler for small gaps and joints Fills gaps and openings to prevent drafts Provides a sound surface for caulking projects Made of