With getting aftermarket headers and catpipe, the O2 bungs are further back from where it was stock. These extensions save you from hacking your sensor (which I did) and potentially throwing a CEL (which mine did within the past couple of months).
That "wire housing" RaceFace, comes with the extension. It's just regular wire loom to protect from the elements (ie. water).
As of 5am Feb. 8, the site still hasn't changed. Boo! They were just yanking my chain.