From techeblog:
One of our readers just sent in an interesting video of the FN F2000, a futuristic looking “assault rifle manufactured by Fabrique Nationale de Herstal (FN Herstal).”

The F2000 platform has a bayonet lug mounted near the muzzle, and has an adjustable gas regulator with two settings: “normal” for standard ammunition meeting SAAMI or NATO specifications, and “adverse” to send more gas into the system to ensure proper functioning when fouled or when using out of spec ammunition. The chamber, rotating breech block, and ejector mechanisms can be accessed by flipping up the access cover, or known affectionately by many operators of the F2000 as the “toilet seat” cover