Deflecto Metallic Duct, Multi Layer, Super Flexible, 4" x 20', Silver (F0420B/2) 4" x 20' 5-ply flexible aluminum duct Designed to replace vinyl ducts, fire retardant with no exposed polyester The flexible aluminum duct is easy to install Fire resistant, be sure to clean ducts over time Operating temperature range 0 - 265 degrees fahrenheit