The inline filter is suitable for CPAP devices. It is used in combination with the machine's -in inlet filter to deliver very clean air. The outer diameter of the connector end: 25mm. The inner diameter of the female connector end: 22 mm. Suitable for 22 mm pipe making machine. Installation and replacement are quick and easy. The filter is connected between the air or outlet of the machine and the . Best Results: Keep the air inhaled by the CPAP machine clean for the best therapeutic effect. A set of 6 filters. Does not contain . Each filter is individually and sealed. Material:ABS colour:As Shown Package Contents: 6 x filters Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.