What Does Mechanical Transfer Registered Jack Mean?
A Mechanical Transfer Registered Jack (MT-RJ) is a connector used for fiber optic cables. They are very small in size and hence are particularly useful in small-sized devices. MT-RJ connectors carry two fibers, and are available in two designs, with mating pins (male) and without (female).
Techopedia Explains Mechanical Transfer Registered Jack
A Mechanical Transfer Registered Jack is a very efficient, high-density, low-cost, and lightweight optical fiber connector that has become widely used in network hardware. The design of MT-RJ is very close to that of the RJ45 connector used in Ethernet networks, however the MT-RJ is smaller in size and consequently lower in cost. It is slightly smaller than a standard phone jack and is very easy to connect and disconnect. Compared to older types of fiber optic connectors, the MT-RJ offers lower termination cost and greater density for cable management hardware.