This SAE Recommended Practice covers the tubing intended primarily for use as hydraulic brake lines on motor vehicles. It covers materials, manufacturing processes, and general properties required to meet the wide range of service encountered in automotive applications. To meet this need, it must be formed, assembled, handled, and installed in accordance with sound engineering and manufacturing practices. This specification covers only the basic tubing and does not include attachments such as protective armor or end fittings. This document is not intended to be used for quality control purposes. Design guidelines are shown in Appendix A.