The BlueSeal Air Curtains from Thermo King are a climate-control solution designed for trailers, box trucks, and vans. The curtains can keep both hot and cold temperatures inside refrigerated trailers or trucks while the door is open. The BlueSeal curtains are an alternative to vinyl trailer curtains and provide a driver-friendly separation between the truck and the outdoors while retaining the trailer temperature during loading and unloading, and also keeps dust, dirt, smoke, and insects out of the cargo area.