Compatibility: Nispira HME filter is an inline humidification solution unit for use with CPAP & BiPAP Machines and CPAP Masks, Z1, Z2, Dreamstation, Easy to Install: To install a Heat Moisture Exchanger for therapeutic use, connect the large diameter end of the HME to your mask and the smaller diameter end to your CPAP tube. Be sure both connections are full seated and secure. Your HME is now ready for use Replacement: HME Filters should be changed about once a week for best results. Storage: When not in use HMEs should be stored a sealed plastic bag (i.e. a ZipLock). The HME will immediately begin to collect moisture and humidity when exposed to air. Each filter is individually sealed to keep away from air contact. Outer diameter on both ends: 25mm / 22mm. A pack of 6 filters included. Quality meets or exceeds leading national brand Nispira HME filter is an inline humidification solution unit for use with Z1, Z2, Dreamstation CPAP & BiPAP Machines and CPAP Masks. It is a waterless humidification that requires no additional power and takes up very little space. A great alternative to large humidifiers. The HME Humidifier Filter for CPAP & BiPAP therapy capture the heat and moisture from the air and exhalations, preserving and increasing humidity to prevent your airways from drying out. HME Filters are a great option for travel. Just simply attach the HME between your mask and your standard CPAP or BiPAP tubing. After that, turn on your machine and experience a steady flow of humidified air. HME Filters should be changed about once a week for best results. Outer diameter on both ends: 25mm / 22mm. A pack of 6 filters included.