See Through Fuel Filters trap particles as small as 15 microns. They can be quickly installed inline to trap dirt, rust and the usual assortment of gas tank glop before it gets into your carburetor. The fuel inlet/outlet is stepped to accommodate stock 4mm fuel line or 6.5mm high performance fuel line. The clear plastic outer shell provides a visual check of your engines fuel system. Make certain to include a new fuel filter with your next tune-up.