The Transcend AirMist HME (Heat Moisture Exchanger) provides pass over humidification for use with your CPAP therapy. With its compact, lightweight design it is designed for Transcend Micro Series CPAP Machines; but it can also be used with most CPAP machine where heated humidification is not available. Simply attach it to your CPAP device, and you’re ready to experience the next level of comfort.