This recommended practice documents dimensional metric specifications for hydraulic brake system tubing with flared ends, threaded ports, male tube nuts, and banjo bolts for the interconnection of major components in automotive hydraulic brake systems. Banjo blocks are not covered by this recommended practice. The purpose of this document is to recommend preferred metrically dimensioned components, (including alternative choices) that are intended to be functionally compatible with International Standard Organization Specification ISO 4038-1977 (E). Some applications may require sizes or forms other than those shown herein, and this document does not preclude such other details when they are required.