ventilation system, collar saddle/ duct/ vent duct/ shsize:80mm-400mm material: gavalnised steel purpose: HVAC, inlet and -ventilation system-Our main products are pressed HVAC fittings,air duct,ship duct, vent duct, coupling and special pipe fittings. collar saddle with gasket and without gasket are both available. Collar saddle with gaskets(ventilation system)