No-caulk flashing with galvanized steel base exclusive 1-piece construction insures a positive leak-proof installation every time. Elastomeric collar allows the vent stack plenty of room for expansion and contraction. Galvanized base is made from 24-gauge deep drawing steel extra high with no seams. Easy- to-install, the flashing slips over the vent stack and automatically adjusts to pipe size and roof angle and remains perfectly flat on the roof.