It's a timer that works in reverse. Turn the knob to the desired amount of time, and your power heads/pumps that are plugged into the attached plugs will turn off for that amount of time. When the time runs out, the power heads/pumps turn back on.

It works great! But, I have a maxi-jet mod plugged into it, and I have trouble getting it going again properly when the power kicks back in. Besides, my fish seem to go and hide whenever I turn it on (power heads off). MY fish actually eat better when there is more flow.

Looking for $35 or possible trades. (Pics are at the bottom of the link below.)

http://maast.org/forums/showthread.php?t=42829