It is Strong™ Open-Face Female-to-Female Coupler for Ceiling Mounts with 1-1/2 inch NPT Threading. Includes set screws to lock down the pipes' rotation so you can set it and forget it. Ever run across an install where not all of the wires can feed in thorugh the top of the pole Picture this: a drop ceiling situation where the low voltage wiring can stay above the ceiling and hidden, but the power can't due to code. The SM-CEILING-OFC an excellent solution to join two pipes together and has an open face to offer an access point to the extension pole. Simple. Clean. Strong.