This part usually threads into the output of the needle valve with 10-32UNF thread. Accepts a 1/4 (outside diameter) tubing. Right Angle. Swivels 360 Degrees.
This part goes between the regulator and the solenoid. The 1/4 side is threaded into the regulator's 1/4 NPT and the 1/8 side goes into the solenoid manifold.