The Lambro 3-1/4 In. x 10 In. galvanized steel rectangular wall stack duct used for HVAC systems or range hood venting between wall studs. The duct is made of zinc-coated 30 gauge galvanized steel and provides advanced corrosion protection and has a snap lock seam with pre-installed s-cleats. Install using sheet metal screws (not included) and it is recommended to seal seams with code approved mastic, sealant or duct tape (not included).