Dundas Jafine CHK100ZW CHK100ZW6 Vents, 4-Inch, White Directs warm, moist air from electric clothes dryers back into your home Safety valve that helps to eliminate back pressure. The ProFlex dryer transition duct in this kit is UL approved for safe dryer venting This product should not be used with gas clothes dryers This product should not be used with gas clothes dryers