You’d be amazed at the dirt and debris that can work its way into your gas can - and from there, into your fuel tank. Twin Air’s monofilament screen pocket inserts in your tank to catch particles as small as 40 microns (.00165”) while allowing the gas to flow freely. The flange is custom-sized for each modern 4-stroke model to ensure a leak-proof seal. Just remove the filter periodically, turn it inside-out, and clean out the debris that COULD have been in your engine. Twin Air's latest product features a custom shaped adaptor for each model that fits securely under the gas cap, creating a leak-proof seal. The filter media traps dirt or debris that can enter into your fuel system from re-fueling.