Premium disposable fine filters compatible with Philips Respironic Dreamstation Go CPAP machine. It captures dust, pollen, pet dander, and other invisible contaminates from the air. Filter approx. dimension: 1.37" x 1.31" x 0.35". Total 12 replacement filters included. The filter can be reused by rinsing it with clean water and letting it dry. Suggest to replace the filter every 30 days to keep the air clean through the machine.