ADVANTAGES OF REUSABLE FILTER SLOTS - Reusable and easy to replace. They make filters for your machine more cost-effective and can reduce plastic pollution to be friendly to environment.FOAM POLLEN ULTRA FINE - The foam version is to block large particulate matter. The ultra fine version is to block fine particles. Use them together to provide the cleanest air.CLEAN AIR FOR HEALTHIER LIFE - Our kit is designed so as to provide you and your loved ones with the cleanest air to maintain the health of your lungs and keep the potential diseases away from you.Reusable Filter Slot Replace Once every 3-6 months,Disposable Ultra-Fine Filters Replace every 2 weeks.Specifications:Applicable models: For Phillips Respironics dreamstation DS500 / 700, etcColour: blue+whiteMaterial: ABS+cottonSize: 6.8x6.8cmPackage Contents:18 x Reusable Filter Slot Replace18 x Disposable Ultra Fine FiltersOnly 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.