The Thomson weigher/bag filler uses a heavy duty foot switch to start the weighing cycle. Simply press to start. The vibratory feed starts filling in mass speed mode,which means it fills the bucket fast. It then hits a pre entered set point, usually about .5lb from the target weight, and switches to dribble mode dribbling the product up to the target weight and shutting off. You then place your bag over the scale hopper spout and fill it. Then press the foot switch and start the cycle over again. Each mode, mass, and dribble, has a speed control rheostat under the controller.