For general purpose venting applications. 181 Class 1 air connector - UL listed and labeled Tear-and puncture-resistant aluminum foil For installation in lengths not over 14 feet Do not use for dryer venting Color/Finish Family: Silver Type: Flexible Diameter (Inches): 4.0 Maximum Length (Inches): 240 Duct Material: Foil Insulated: No Insulation Material: N/A (not insulated) Warranty: 1-year limited CA Residents: Prop 65 Warning(s): No R Value: 0.0 Safety Listing: UL safety listing UNSPSC: 72151200