FITS: 2017-2021 FLHT,FLHR,FLTRX,FLTRU,FLTRK,FLHX,AND H-D TRIKE MODELS GET THE MOST OUT OF YOUR M-EIGHT! The FEULING billet dipsticks vent/breathe excessive crank case pressure from the oil tank through a PCV style breather, consisting of an oil separator system, perforated disc, replaceable filter element and umbrella flapper valve. Feuling vented dipsticks screw into the factory oil fill spout as a stock replacement part. These breathing dipsticks remove unwanted build-up of blow by pressure in the oil tank. Blow by is pressure that is forced past the rings and cylinders, pushed into the crankcase and then forced into the oil tank. FEULING dipsticks help remove this unwanted pressure through a (CVS) Crankcase Ventilation System. Test results show a decrease in engine oil sump levels, more freely/smoother revving engine, increased MPG and decreased blow-by. NOTE: All internal combustion engines have a certain amount of blow by. Larger cubic inch engines as well as engines with worn and or loose ring clearances will have increased blow by. Engines pushed to their limits will also produce excessive build up of power robbing blow by.