They are longer front-to-back than the OEM, but they're the same diameter light (4"). They can be manipulated so that the back side of the bucket *just* touches the wind screen. Only disadvantage I've experienced is that I have to tilt them downward to remove my wind screen.
They're easily as bright as stock lights, but you can change the lamps out for some brighter LED lamps too. To get these on the bike, I chose to drill through the little arm and run a bolt through it and the stock "U" shaped attachment for the OEM lights. If I were doing it over, I might try to fabricate a new arm to replace the one that comes on this light, or a little bracket piece that moved the attachment point for the aux lights forward of the support tube.
They're way cheaper than the OEM parts, but I think they look better.