Builder's Best WMF621 Foil Duct

Wire helix multi ply foil duct designed for low to medium operating pressures in HVAC systems Class 1 Air Connector label meeting NFPA (90A and 90B). Tear and Puncture Resistant Encapsulated wire helix does not unravel when cut to length Air tight construction and smooth inner core Steel Wire Support Note: Not for use to vent appliances for cooking, heating, and clothes drying unless approved and recommended by the appliance manufacturer PRODUCT SPECIFICATIONS Wire helix duct with steel wire support Multi-ply design of aluminum/polyester laminate and metalized polyester PRO Performance LevelUL® 181, Class 1 air connector label; UL® sticker every 10 feet 3" dia. has ¾" pitch; 4–12" dia. has 1" pitch Maximum velocity rating 5000 fpm