We've used that on our rc car motors. Off road racing buggies and trucks have to filter a tremendous amount of dust and dirt. The engines, being a fraction of the size of our saws, is much more easily ruined. However, there is still quite a bit of experimenting with different materials. One commonly used is the colored, "Ace" type bandage that adheres to itself when stretched and pressed down. It makes a great outer filter and would be ideal for filters like the ones used on my 440 and 441. It's pretty open, but it catches all the biggest particles without choking the engine.