These intake filters are designed for the ARYA Airtivo and ARYA Airtivo Max portable oxygen concentrator, which help to block dirt and dust particles from getting into your device's air intake. It's important to remember to replace these intake filters every 3 months of daily use. However, depending on your environment, if you have a higher exposure to dust or dirt then you should periodically check the air filter. If you ever notice the filter turn a grey or brown color, that would indicate that it's time to replace it. Regular filter replacement helps maintain optimal performance of your portable oxygen concentrator by ensuring clean air intake and protecting internal components from debris buildup.