NVT, FLEX expansion kit, connects through 2 or 4-pair UTP, up to 100 Mbps, 50 W power up to 2 Km, includes 1 x FLEX Base Unit, 1 x FLEX-Link adapter and 1 x 60 W, 55 power supply, IEEE 802.1x, EN 50121-4 (Railway/Subway)

See the table in the documentation for a list of transmission distances as a function of the use of 2 or 4 pairs and as a function of the maximum power deliverable