a metal or plastic conduit a round, rectangular, or square shape seams or joints connecting separate sections vents or grilles to release air a connection point to an appliance or other ducts insulation to prevent heat loss
duct which is a metal or plastic conduit duct which is a round, rectangular, or square shape duct which has seams or joints connecting separate sections duct which has vents or grilles to release air duct which is a connection point to an appliance or other ducts duct which has insulation to prevent heat loss