The inline filter is compatible with CPAP devices and works in conjunction with the machine's built-in inlet filter to help deliver cleaner air. The outer diameter of the connector end is 25mm. The inner diameter of the female connector end is 22mm, suitable for 22mm tubing. Installation and replacement are quick and easy. The filter is placed between the air inlet or outlet of the machine and the CPAP hose. For best results, use to help maintain clean air intake for improved therapeutic performance. This pack includes 6 filters. The filters are latex-free, with each one individually sealed. Material: ABS Color: As shown in image Package Contents: 6 x Filters Note: Only the items listed above are included. Light and display settings may cause slight color variations between the image and the actual item. Measurement may vary by +/- 1-3cm.