Oxygen Concentrators are pretty resilient machines. They are designed to run non stop, if needed. They are very easy to use and do not require much maintenance at all. Overly dirty filters can restrict the air going into your Oxygen Concentrator. This can cause the machine to run improperly. It may also cause a "Low Oxygen" light to illuminate on your machine. Replacing the air filters is a cheap and easy way to prolong the life of your machine. It is almost like an oil change for your car. If you do it more often than needed, it will not harm your machine, but prolong it's life! But if you neglect the filter changes, it can drastically shorten the life of your machine. Depending on the machine you own, there is generally a foam filter on the cabinet. Once you notice the filter is dirty, You simply remove it from the cabinet, rinse it off in your sink, and let it air dry before placing it back in the cabinet. Inside the machine, there is typically a pleated HEPA filter in a plastic case. You never clean this filter, you just throw it away and replace it with a new filter. Inside the machine is a Bacteria Filter. It is located behind the flow meter, and looks kind of like a child's spinning top toy. These filters have recently been dubbed a "lifetime filter" which means it should not need replacing. If you are able to, we still recommend replacing it at least every couple years. The filters we provide are all 100% made in the USA and are individually packed for cleanliness. We ship them out daily with the United States Postal Service. Shipping is FREE on our filter kits and should arrive within two to five days after purchase!