Devos II was a planet that during the 2370s hosted a Son'a outpost. During the Dominion War a ketracel-white facility was located there.
In 2375, the Dominion believed that the Federation had been made aware of the existence of the facility. Due to this, Weyoun was forced to dispatch Dominion forces to defend the outpost rather then pursue the USS Defiant fleeing the area. (DS9: "Penumbra")