Frost King 3/8″ Caulk Saver Poly Foam Backer Rod 350-Foot Roll $18 at Amazon

amazon.com has Frost King 3/8″ Caulk Saver Poly Foam Backer Rod 350-Foot Roll for $18.23 with free shipping on orders of $35+ or Prime.

  • reduces the amount of caulk needed to seal or fill large openings and compatible with most caulking.