An improved shower arm having an elbow portion adapted to fluidly communicate with a shower head and an arm portion adapted to fluidly communicate with a water supply. The arm portion is pivotably coupled with the elbow portion about a long axis of the elbow portion, with the long axis of the elbow portion and a long axis of the arm portion forming an angle. Also, the shower arm includes a locking mechanism having one or more sets of splines to securely lock the relative position of the arm and elbow portions. The splines may be coupled and decoupled by a variety of mechanisms, including: hydraulic pressure generated by a restrictor plate; a spring forcing the sets of splines together; and a pair of magnets.