These chrome cylinder head breather tubes are a must when installing an aftermarket air cleaner on bikes with the so called "Thru-the-head" breather system. Simple bolt-on construction comes complete with required hardware. Big Twin kits include 2 sets of breather bolts to allow fitment on 1993 thru 1999 Evolution, 1999 thru 2017 Twin Cam, S&S V-style as well as S&S T-style engines. A breather filter is not included, but strongly recommended when you do not route the breather hose to the air cleaner. The thru-the-head breather for 1991 to present XL Sportster models is a tube only, intented to upgrade from the common loose banjo's and hoses as found in many aftermarket air cleaner kits.