is a brand of "Generator Transfer" switch that is required by law (here) if you're going to use a generator. Too many ppl screw up and "backfeed" juice to the power lines endangering workmen and other neighbors.
It's not cheap, but not hard to hook up either
http://www.gen-tran.com/about_us.htm
from their site
"A transfer switch makes using a generator more safe and convenient – no matter what size. The National Electrical Code mandates that a transfer device be installed with all standby power systems including portable generators. During a power outage, a transfer switch safely isolates those circuits using generator power from the rest of the house, so the danger of back feeding the electrical utility is eliminated. By installing a transfer switch with your load center and connecting a portable generator to the transfer switch, you can run selected appliances such as a furnace, well pump (which cannot be run with standard extension cords), sump pump, refrigerator, television, computer and more during a power outage, depending on the capacity of your generator. "