From The Manufacturer/Wikipedia/People Smarter Than Us:
RFB stands for Rifle, Forward-ejecting Bullpup. Why forward-ejecting? Because it allows the RFB to be the first truly ambidextrous 7.62 NATO Bullpup ever developed. The patented, dual-extractor system maintains control of the case from the moment it leaves the magazine and upon firing, pulls the fired case from the chamber and lifts them to push them into an ejection chute above the barrel, where they exit. The Bullpup configuration and tilting-block mechanism allow the 18″ model to be only 26.1″ long, or as much as 14″ shorter in overall length than its competitors with equal barrel lengths.