Bought a 400/4 with one fitted many years ago, a quarter turn from tickover to full throttle, and basically it was crap! Cripplingly heavy to use, tried a lighter spring, but then it wouldn't shut down properly, and always very jerky in action. Also, because of the diameter of the barrel which the cables pull round, it also limited the pull of the front brake, which was downright dangerous! I seem to recall it was made by Tomaselli, and I took it off after a matter of hours. Incidentally it was typical Italian quality, utter garbage!