Due to volume increasing of RMT, we need to pick 2carrier for 2015.(One is
main carrier and the other is back up)
However for USA shipment, we have to set MQC(Minimum Quantity Container)
and carrier provide space following it.
Also we have to achieve MQC otherwise we'll be punished from USA
government.
To achieve MQC, we need you to use both carrier for equal volume.