The inline filter is compatible with CPAP devices. It works in conjunction with the machine's built-in inlet filter to help deliver clean air. The outer diameter of the connector end is 25mm. The inner diameter of the female connector end is 22mm. Designed for use with 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, maintain clean airflow into the CPAP machine to support effective therapy. This package includes a set of 6 filters. Latex-free. Each filter is individually sealed. Material: ABS. Color: As shown. Package contents: 6 x filters. Only the listed items are included; other products are not part of this package. Note: Lighting and display differences may cause slight variations in color between the image and the actual item. Measurement tolerance: +/- 1-3cm.