This self-contained, self-powered unit was designed specifically for potentiated startle. With a cycle rate of 30 Hz, aversive stimulation durations as short as 200 ms ensure stimulation across the entire floor. Output shock current is adjustable in two ranges, 0 to 1 mA or 0 to 5 mA, using a two position ‘Range’ switch and ten-turn potentionmeter (output current adjustment knob).