Controlled via external 0..10VDC signal. Electric duct heaters EKA are designed to heat clean air in ventilation systems. Casing is made from aluzinc coated steel which is high temperature proof. Heating elements tube is made from stainless steel AISI 304. In heaters are installed 2 protection thermostats, screw terminals for easy connection. Casing is with rubber seals for duct connection.