100% appropriate for CPAP machine. Quick install and easy to use. Recommended 6-month replacement: It is advised to replace the filter and valve every 6 months. Universal compatibility: Filter replacement kit features an exquisite design, perfectly compatible with SC1200 and SC2 machines, delivering the same performance as original. Convenient to install: CPAP filter kit is designed to replace old or damaged filters, easy to install without additional tools, and ensures no risk of leakage. Easy carrying: CPAP machine filters require no special storage bag, compact, lightweight, and convenient for travel. Material: Plastic Color: Grey Package contents: 4 x Filter 4 x Check Valve Assembly Only the above package content is included; other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture to appear slightly different from the actual product. Measurement allowance is +/- 1-3 cm.