3", Aluminum, No Chalk Roof Flashing, .032 Metal, Slides Over Pipe For 40 Degree Rustproof, Non-Fading Sealing Collar, 18" x 18" Base, Rated 180 Degrees Fahrenheit, Continuous Heat, Approved For Type B Installations, UPC, SBCCI & BOCA Listed, Not For Hot Mopped Or Built Up Roofs.