Each breather is secured with an O-ring at the heads, while passing through the backing plate into the mouth of the throttle body using proprietary breather tubes. This kit comes with a one-piece backing plate, breather tubes, specially designed filter, filter top, seals, a reservoir and all necessary hardware. The new patent-pending hidden breather backing plate technology is a superior system compared to our original patented system. High-performance filters are constructed from pre-oiled black cotton for improved airflow and filtration. An air inlet with a smooth radius ensures maximum air flow. 2020-2021 Harley-Davidson Softail Low Rider S FXLRS - - 2020-2021 Harley-Davidson Road Glide Limited FLTRK - - 2020-2021 Harley-Davidson CVO Tri Glide FLHTCUTGSE - - 2020-2021 Harley-Davidson Softail Standard FXST - - 2019-2021 Harley-Davidson Electra Glide Standard EFI FLHTI - - 2019-2020 Harley-Davidson FXDR 114 - - 2018-2021 Harley-Davidson Softail Fat Bob 114 FXFBS - - 2018-2021 Harley-Davidson Softail Fat Boy 114 FLFBS - - 2018-2021 Harley-Davidson Softail Slim FLSL - - 2018-2021 Harley-Davidson Softail Sport Glide FLSB - - 2018-2021 Harley-Davidson Softail Street Bob FXBB - - 2018-2021 Harley-Davidson Softail Heritage Classic FLHC - - 2018-2021 Harley-Davidson Softail Heritage Classic 114 FLHCS - - 2018-2021 Harley-Davidson CVO Road Glide Custom FLTRXSE - - 2018-2020 Harley-Davidson Softail Low Rider FXLR - - 2018-2020 Harley-Davidson Softail Breakout 114 FXBRS - - 2018-2020 Harley-Davidson Softail Deluxe FLDE - - 2018-2019 Harley-Davidson Softail Fat Boy FLFB - - 2018-2019 Harley-Davidson Softail Fat Bob FXFB - - 2018-2019 Harley-Davidson Softail Breakout FXBR - - 2017-2021 Harley-Davidson Road King Special FLHRXS - - 2017-2021 Harley-Davidson Road Glide Special FLTRXS - - 2017-2021 Harley-Davidson Street Glide Special FLHXS - - 2017-2021 Harley-Davidson CVO Electra Glide Ultra Limited FLHTKSE - - 2017-2021 Harley-Davidson Tri Glide Ultra Classic FLHTCUTG - - 2017-2021 Harley-Davidson Electra Glide Ultra Limited FLHTK - - 2017-2021 Harley-Davidson Freewheeler FLRT - - 2017-2021 Harley-Davidson Road King EFI FLHR - - 2017-2021 Harley-Davidson Street Glide EFI FLHX - - 2017-2021 Harley-Davidson Road Glide Custom FLTRX - - 2017-2021 Harley-Davidson CVO Street Glide FLHXSE - - 2017-2021 Harley-Davidson Electra Glide Police FLHTPI - - 2017-2019 Harley-Davidson Electra Glide Ultra Limited Low FLHTKL - - 2017-2019 Harley-Davidson Road Glide Ultra FLTRU - - 2017-2019 Harley-Davidson Electra Glide Ultra Classic EFI FLHTCUI