For all gutters, down spouts, heating and AC ducts, and other seams in sheet metal surfaces. Cartridge has 3" spout. Composed of SBR rubber and high quality resins, which cures to form a tough, rubbery seal that expands and contracts with the change of weather without cracking. Covers 31 ft at a 1/4" bead and 14 ft. at a 3/8" bead.