Add-On Sanitation Unit Good For Cold Stores , Seafood Factories And High Humidity Facilities Holding Door Openings Air Barrier Height 2.0 To 2.4m With Three Level Wind Speed Control At 9 , 11 Or 13 m/s And Air Volume From 1108 To 2211 m3/h Waterproof Epoxy Coated PCB And Lightweight Aluminium Housing With A Damper Adjustable Up To 50 Degrees Works With Automatic Sensors And Limit Switches Reduce Manpower Labour To Police Doors And Chase Temperature Loss At Every Opening