I bought Mikrotik RB912UAG-OUT, I open it to check that it is the same board as standard 912UAG and I’m very surprised because there is 4x external antenna connectors (2x RP SMA, 2x MMCX). What does it mean ? I saw some MIMO 4x4 antennas with sign Made for Mikrotik: http://www.wireless-instruments.com/en/produkty/15/56/antennas-5-ghz/mimo/directional/wibox-pa-d4m5-20hvx.html, but I never heard about even MIMO 3x3 Mikrotik RouterBOARD. May be somebody know more about it. Photo of my board: