Long, long ago in a galaxy far, far away Campagnolo supplied you with these exact cable stops when you purchased a new set of Ergopower levers or a complete cable kit. But given the fact that carbon fiber frames are almost universally made with in-line cable adjusters/stops, these downtube cable boss-mounted stops have gone the way of the dinosaur. So Campy quit including them with levers & cable sets.

The problem, though, is this: If your bike does indeed have downtube cable stops, you MUST have these, or you can't run Ergopower. They bolt into your bosses to serve as cable stops for your derailleur cables. They have threaded adjuster barrels so you fine-tune your front and rear derailleur cable tension (and thereby adjust your shifting) while you ride. You get two stops (they are left and right-specific) and the bolts to attach them to your frame.