The bubbling humidifiers for oxygen therapy series CH/200, TR/200, MAK/300 and MAK/500 are devices used to increase the relative humidity in the treatments with medical oxygen, both in hospital and at home. Medical oxygen, as it is normally supplied from hospital plant outlets or cylinders, has not a sufficient degree of humidity to be physiologically tolerated by the patient’s airways without collateral consequences. Hence the need to add on oxygen supply devices, such as the flowmeters, suitable devices for the humidification of the gas during dispensing. Humidifiers for oxygen series CH/200, TR/200, MAK/300 and MAK/500 are manufactured with both the transparent jar and the cover with bubbler in polycarbonate. All fitments are in brass and they can be sterilized in autoclave at 121°C for 15 min. They guarantee, in conjunction with flowmeters Rs, RsP and EASYMED®, an easy use and great versatility, combined with an extreme economy. They are supplied in different options of capacity (200 ml, 300 ml and 500 ml) and with optional threads in the input connections, this to satisfy the most varied requirements and needs. The model TR/200 can also be realized in PSU where higher value of sterilization temperature is requested (134°C - 18min).