Builder's Best WMF621 Foil Duct UL181 Size:4'' x 5' (varies by depth of soil

(varies by depth of soil layer and project)

Through Hardened Durability - Avg 58-60 HRC

can be used in closed or ventilation position

Caps are over-sized for more protective coverage

Builder's Best WMF621 Foil Duct UL181 Size:4'' x 5' (varies by depth of soilWire 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