Rear Brake Line Kit. Stainless steel brake lines are typically the first brake upgrade you should make. Stock rubber lines will break down and expand, causing a spongy brake feel or worse. Steel lines eliminate expansion which results in consistent feel and performance. Aftermarket stainless steel brake lines may look similar, but they are not the same! Every GBrakes stainless steel line is made with only DuPont™ virgin-grade PTFE inner core, 64-strand braid and GBrakes fittings are probably the most expensive, but highest quality you can find on the planet. Rear brake line kit (front lines sold separately). These are the same fittings that Ferrari, Lamborghini and Ducati uses, among a few other high end O.E.M.'s. Kits are bike-specific and are tailored to each bike for perfect fit and finish. Pre-positioned banjo fittings.