When challenged with a projector or TV mount installation in an open-ceiling scenario, the SM-CEILING-TM provides the foundation necessary to connect the extension pole and get the job done quickly. With 11.5 threads per inch, this truss mount adapter will work with any poles that use 1.5 in. NPT. The SM-CEILING-TM works with round, square, rectangular or I-beam supports, up to 3" wide by 3 1/2" high, using an adjustable adaptor plate for a tight, secure fit. Great for installing into open ceiling situations. Includes set screws to lock down the pipe's rotation so you can set it and forget it.