Heavy Gauge 4 in. Pipe is used to vent boilers, furnaces and hot water heaters. Available in a variety of common lengths, diameters and gauges to help make your next HVAC project a success. A simple snap lock design and sturdy galvanized steel construction combine for a quick and secure installation that you can rely on.Easy-to-install snap lock designCrimped end with a stop-bead for a secure interlocking fitSturdy 26-Gauge, galvanized steel constructionAlways seal seams with building code approved sealant or duct tapeAlways insulate ductwork for greater system efficiency and comfort