Adjustable Swing Arm Coupler Wall Mounnt Tub Faucet Parts | Renovator's Supply Tub Supply Lines. Obtain your Tub Supply Lines here now. Adjustable Swing Arm Tub Wall Supply Line Coupler Pair Chrome plate over brass means these supplies will last NOTE: For inside tub wall installation ONLY. Adjust center to center from 2 1/4 in. to 11 in.