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