1. Please check the mounting hole size to make sure this shower arm fits.

You could consult your professional contractors about installation. 

2. Heavy-Duty Solid Brass material for both shower arm and escutcheon / flange.

This 3 inch round ceiling mount shower arm is made of diameter 15/16 inch solid brass pipe.

Flange size is Diameter 2.36 inch X 0.4 inch.

3. Both sides are Soldered 1/2 NPT Tapered Threads.