M-D Building Products Gray Foam Caulk Backer Rod For Door and Window 350 ft. L x 3/8 in. - 5670948
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.