tongue_of_colicab
Veteran
Norbert Haug and a guy from Mercedes High-performance Engines showed the KERS to Martin Brundle (or was it DC?) during the BBC build up to a qualifying session (can't remember which) and it looked very light and very small. Apparently it's not connected to the brakes but the engine.
Ofcourse it looks light and small, all units do (probably because they are ). The company working on the fly wheel kers for williams that put that video online, their unit isnt much bigger than a small ball.