This listing is for ONE (1) Modern issue medical grade, DC Power Supply Transformer. Standard USA AC 110V/220V INPUT. It has variable OUTPUT power levels of 0 to 30 Volts 0 to 5 Amps. It is designed for scientific research universities such is a very clean power source. Power in Slot Car Racing gives each track lane enough power to predictably control throttle response. Cleaner power helps cars to run cooler, quieter smoother, there by lasting longer. Please refer to the manual for specific limitations. This product should only be used by experienced professionals. DIGITAL DISPLAY Allows you to zero in on the best combinations of Voltage Amperage for the class of cars you are running. This allows the racer to go back to the exact power level each time. Very helpful. Fuse-able link, fan cooled AC/AC input voltage selector. Positive, Negative Ground Terminals. Please Be Aware: shipping 5 POUNDS of Heavy Duty Power! Sold as is. Descriptions are very accurate; No Returns. PLEASE ASK QUESTIONS BEFORE YOU BUY IF YOU ARE UNSURE. We ship promptly professionally. We happily combine orders refund any excess s/h immediately upon shipping. We can always provide tracking. I charge $1 for expert handling/packaging, actual shipping. We ship out of the country almost daily. Please refer to our feedback, social media or time selling HO slot cars for assurances of a good honest deal. Happy motorin' thanks S'lots from Bob at Slot Car Central in SYR. We Know H.O.