The new RB604 is an expansion for RouterBOARD 600 and also the RouterBOARD 500 series. It attaches to the RB device to add 4 additional miniPCI slots, your RB/600 can now have 8 miniPCI slots total!
The RouterBOARD 600 is the high performance wireless platform. It has four miniPCI slots and three gigabit ethernet ports and it is the fastest wireless board that MikroTik has ever made
The RouterBOARD 604 is a daughterboard for the RB532 and RB600. It attaches to the RB532/RB600 (see picture) by means of special daughterboard connector and adds four more MiniPCI slots
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