This 6 x 6 in. adapter plate has a 1.5 in. NPT threaded pipe coupling that is slotted for safely routing signal cable through pipe interior. It can be used with any standard 1.5 in. NPT pipe or with one of our 1.5 inch adjustable-height suspension adapters (APP-1321 or APP-2446) for drop distances of more than 3.8 ft.