Professor Motor "SCALE RACER SUPER PRO" Model Electronic Slot Racing Controller -  Recommended Operating Voltage Range : 14 to 19 volts - POSITIVE polarity - Includes 25 Ohms variable brakes, variable sensitivity (single knob adjust), high capacity dual external aluminum heat sinks, heavy 13 gage silicone leads & solid copper alligator clips with color coded boots - "SUPREME Series" external transistor based technology - Recommended Applications : HO, 1/32 & 1/24 Scale Home & Club Racing through Group 12 Motors