Oxygen concentrator intake filters capture dust, impurities, odors, and other particles in the air, providing clean oxygen to users. Safe & eco-friendly for easy use. Multi-layer filter element is composed of high-density refractory fiber filter paper and filter cotton. It can effectively absorb impurities in the air to keep your oxygen supply pure. Easy installation, simply remove the old filter and insert the new one to keep your oxygen concentrator running smoothly. Size: 121mm L x 60mm W x 49mm H. Outer diameter is 22 mm, inner diameter is 20mm. Compatible with 5L, please confirm your machine model before purchasing. 3 pcs in package. Note: This product is disposable and needs to be replaced regularly to pure oxygen is available. Color: Gray & White Material: plastic Package Contents: 3 x Repalcement Filter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.