• Nispira Disposable Polyester filter Replacement compatible with HDM Z1 Z2 Basic Travel CPAP Machine 
• Compared to original Part HD60-3021 
• It helps remove impurities from the air as it is drawn into the CPAP machine 
• Suggest to replace every 30 days. Dimension 3.5 x 2.0 x 2.0 
• A set of 12 Filters included.