VINTAGE CAR BRASS BRAKE PIPE UNIONS 
PIPE FITTINGS AS SHOWN
 Some 3/8" x 24TPI UNF thread

to fit pipe 3/16" outer diameter

                                                  Suitable for a large range of classic cars 

                                                  vehicles like; Austin, Ford, Jaguar, MG,                                                 Triumph, Morris, Mini, Vauxhall,                                                     Wolseley, Oxford, Cowley and often used in kit cars

Just found another box six bleed nipples added shown last image 3/8" x 24UNF