This SAE Recommended Practice is intended to provide a design, interchangeability dimensions, testing procedures, performance requirements, and minimum identification for gladhand-type air line couplers used to connect the brake systems of trucks, truck-tractors, trailers, and dollies when these vehicles are joint to operate as a combination unit. The purpose is to provide coupler halves for brake lines on one vehicle that will be identified and compatible with the coupler halves on the brake lines of another vehicle.