The SXT Sixpack contain five SXT-5HPnD and one SXTG-5HPnD-SAr2 (SXT-SA [sector antenna])
The SXT-SA has level 4 for multi-point and the SXT-5HPnD has a level 3 for point-point
you must set the sxt-sa as ap-bridge and the other as station-wps
you can use my example configuration for max throughput:
http://forum.mikrotik.com/t/2-sxt-ppp-one-way-signal-is-bad/74620/1