ResMed S9 Head Unit controls many functions, including Respirator Operation. Has LED screen with large easy to use dial buttons (complete instructions found online). Has built in filter (replacements found on Amazon as well as Breathing masks - has standard push on tip use your most brand masks - ResMed masks work best). Also comes with ResMed H5i Humidifier unit (attached to control unit). Also includes factory power pack, all as seen, mint in condition. Head unit uses standard SD card, same as used in digital cameras (not included). ResMed Masks, Tubing and Replacement Filters found on Amazon. We ship worldwide from San Francisco bay area.