This SAE Recommended Practice is intended to provide a design@ critical dimensions@ performance requirements@ and identification for gladhand-type air line couplers used to connect the brake systems of trucks@ truck-tractors@ and trailers when these vehicles are joined to operate as a combination unit. Purpose - The purpose is to provide a coupler half for the service (control) and emergency (supply) brake lines on one vehicle that will be identified and compatible with the coupler halves on the service (control) and emergency (supply) brake lines of another vehicle.