Brake unions are standard 3/8" x 24TPI UNF thread. CLASSIC CAR BRAKE PIPE UNIONS x20. If you are not 100% happy with the part you ordered, we will replace the part or your money back. vehicles like; Austin, Ford, Jaguar, MG, Triumph, Morris, Mini, Vauxhall, Wolseley, Oxford, Cowley and often used in kit cars.