Flat insulated hygienic air ducts for installation in confined spaces and low ceilings, extremely flexible, durable and quiet, covered with an insulating jacket of 9 mm thick cellular rubber, with a perfectly smooth Clinside surface for hygienic operation and easy cleaning, available in Flat and round versions. Transport of warm and cold air without condensation and without noise. Insulated couplings, elbows and other components available for convenient, safe and functional installation.