M-D Gray Foam Caulk Backer Rod For Door and Window 350 ft. L X 3/8 in.

The M-D Building Products pro pack 3/8 inch x 350 feet green backer rod acts as a filler in small gaps before applying caulk. It insulates as well as cushions. Use in pavement cracks, wall joints and foundations. Backer rod is easily trimmed to size with scissors.