Very good condition, tested. Great working transformer. This transformer has DC to run your train and AC to run any accessories. It also has pulse width power. Instead of simply starting with a very low voltage and going up as you turn the knob, Aristo power suppliers actually send "pulses" of DC power to the locomotive. As you turn the knob up, the pulses get longer and closer together. The train still starts up slowly (in fact, the "inertia circuit" - another feature - makes sure of that). But the train will generally run a bit more reliably at lower speeds (since nearly full voltage is getting to the train with every pulse). In the meantime, sound systems, smoke systems, and lighting systems all work much better at low speeds than they would with traditional rheostat-only control.