A Media Converter is an active component of the fibre-optic trunk line, which makes it possible to directly connect the cabling made by a Twisted Pair cable with the fibre-optic cabling or the connection of multi-mode cabling with single-mode one in a fibre-optic cabling in the Ethernet Network segment. Thanks to the use of a converter, it is possible to extend the Twisted Pair segment beyond the limit of 100 m. Connection of various transmission media by means of media converters has the added advantage that there are no additional limits with regard to the maximum number of repeaters. The device is also available in the version with an in-built Link Through function. This means that in the case of the connection is cut in the fibre-optical line, there is an automatic break of signal on the side of the twisted pair (and vice versa). The Converter status is indicated by LED. They may be used for localising faults or network diagnosis.