The pedal furthest to the right is the foot throttle. Unlike in automobiles, it can also be controlled from a hand-operated lever ("hand throttle"). This helps provide a constant speed in field work. It also helps provide continuous power for stationary tractors that are operating an implement by shaft or belt. The foot throttle gives the operator more automobile-like control over the speed of the tractor for road work. This is a feature of more recent tractors; older tractors often did not have it. In the UK, foot pedal use to control engine speed while travelling on the road is mandatory. Some tractors, especially those designed for row-crop work, have a 'de-accelerator' pedal, which operates in the reverse fashion to an automobile throttle, in that the pedal is pushed down to slow the engine. This allows fine control over the speed of the tractor when maneuvering at the end of crop rows in fields – the operating speed of the engine is set using the hand throttle, and to slow the tractor to turn, the operator simply has to press the pedal, and turn and release it once the turn is completed, rather than having to alter the setting of the hand throttle twice during the maneuver.