The height configuration of these distribution boxes is flexible and variable, and different rack units (RU) heights such as 1U, 2U, or 4U can be chosen according to different connection requirements. Here, "U" stands for "Unit" and is used to represent the height of network. The fiber distribution box, a crucial component in optical fiber networks, serves a dual purpose of managing and protecting optical fibers while facilitating their efficient distribution. ication and relevant standards over the range of optical wavelengths from 1260nm to 1625nm. Suppliers shall provide information on the likely change in pe fficiently handled and. What is a Fiber Optic Termination Box? The Connection Hub at the End of the Fiber Cable A Fiber Optic Termination Box is a small enclosure located at the terminal end of the fiber where it enters your customer premises. A -10 dB means a reduction in.