The HumidX offers the best in waterless humidificatition. Other HMEs (Heat Moisture Exchangers) are usually placed after the mask vent. With other HMEs, you inhale dry inbound air; then when you exhale, the majority of heat and moisture from that breath, goes straight out the vent instead of back into the mask. With the AirMini and the set up pack adapter, the HumidX heat moisture exchanger is located before the vent. This allows the HumidX to ‘charge’ and discharge with heat and moisture during every breath, providing effective waterless humidification to you.