If you want to add a handheld showerhead and keep your existing stationary head, you'll need a cross-tee fitting with two outlets. One will connect to the handheld unit through its hose, and the other will reconnect to your existing head. Alternatively, you can get a dual-headed option that offers both. And as Epstein explains, many newer models feature "stationary showerheads that come off and become handhelds."