Sashco Round Pre-Caulking Closed Cell Backer Rod Roll, 550' Length  x 1" Width
Sashco Pre-caulking closed cell backer rod coil. Use behind chinking and caulking. Essential for ideal joint design. Helps fill in and insulate large caulk joints and allows the caulking to absorb more movement. Fills the joint so you use less caulk. Fully compatible with all substrates and sealants. Use behind chinking and caulking. Essential for ideal joint design.Caulking adheres to the sides of the joint, but not to the filler rope, which allows the caulking to stretch and compress without tearing or pulling away thus extending the caulk's life and effectiveness. Closed-cell design repels moisture.  Available in round shape. Measures 1"-inch diameter by 550'-feet length.