... for low and medium pressure air conditioning, ventilation, boiler systems. applications&Features Alu Spiro Pipeair duct, ventilation duct*Made ... for low and medium pressure air conditioning, ventilation, boiler systems and chimney liners. Very light with negligible extra load, ... secured using an "INTERLOCK" crimp system."INTERLOCK" crimp systems minimize separation of the duct when it is stretched or ...