Those prefilters are awesome. I've used them on sleds and jet skis for years to repel water and snow. Polaris uses them on the atv's too. They are a fine mesh and eventually clog up and need to be replaced. I use gas to clean them as some cleaners seem to damage them and restrict the flow. They do catch a good bit of the dirt though.
04 ktm 950 adventure GO!!! (blacked out) 1990 Suzuki DrBIG 800 2003 Beta Rev 3 1999 Suzuki intruder 1500 1979 Suzuki GS850G the original adventure bike. 1973 Rokon mark 3 trailbreaker auto 2x2 1980? dt175 2008 Aprilia RXV 450