Speed Bully Motor Speed Controllers bring quality and convenience to your grow environment. Easily control the speed of pumps, routers and most other AC/DC Brush-Type motors. This controller is rated for 5 amps or less and is multi-functional giving you a variable speed, constant and off options. Flip the switch to Variable and use the easy to adjust knob to control the speed of your device. This device is great for controlling air temperature when drawing air from an outside source. The device will not work with a soft or slow-start motor. The speed bully makes controlling fans a breeze.