These filters are disposable! Filters in your CPAP machines are a very important part of your sleep therapy as they serve to remove dust and pollen particles. They were designed for the Resmed S7 Elite CPAP machine, the S7 Lightweight CPAP machine, the Autoset Spirit CPAP machine and the Auto Respond CPAP machine, and the VPAP III and VPAP III ST Bi-Level machines. The package includes 3 filters per package measuring 1.25 inches long and 1.50 inches wide. If you are unsure of the right size filter just give us a call.