StopTech stainless steel brake lines are a great upgrade for your Wrx/STi. Your stock rubber brake lines flex, slowing down response, and performance. Stainless steel brake lines do not flex, and will provide a quicker, and more firm pedal response. Stoptech uses a Teflon inner line that resists pressure, and will not degrade due to exposure to brake fluid. The stainless steel lines also feature a clear abrasion resistant cover for protection against chaffing. They are sold as a set of 4.