SR SUN RISE ARY001 Ceiling Mount Shower Arm Round 300mm Wall Mounted Arm of Solid Brass Chrome Finish The longer thread is standard NPT 1/2" connection Length: 300mm (11.8 inch) Only suibtalbe for Ceiling installation Chrome plating doesn't oxidize or corrode Easy & fast installation, no tool required.5 year warranty Longer thread for ceiling mount. Shorter thread for rain shower head. Need to be installed with teflon tape.