Pure Choice supplied the adapter to allow the use of steel 3/16 inverted flare hard lines with -3 (3/16-inch) AN brake hoses. Note the groove in each for a brake line clip. The brass fittings are called trailer Ts (or branch Ts). They have two female 3/16-inch inverted flare ports and one male 3/16-inch inverted flare connection. The male port supplies the left front brake, the female port connects to the master cylinder, and the other to a line leading to the right front brake.