Use For Adapting A 9/16-18 Inverted Port To A 3/16" Domestic Brake Line.Adapter, Brass, Female(3/8-24 Invtd), Male(9/16-18 Invtd), 100/box Simply Match The Male Side Of The Adapter To The Port Connection On The Dual Master Cylinder And The Female Side Of The Adapter To The Brake Line Connection To Be Made..