i've been installing floodstops/ burstburster 2000 for a couple years now.
the ones i use are the washing machine valves and the water heater valve. they also come in icemaker, dishwasher, faucet shut offs. along with a whole house shut off and remote monitors.
basically it's a motorized ball valve that's controlled by a controller with a water sensor pad.
when water hits the sensor, the controller sends current to the motorized ball valve/valves to close the valve and sets off an alarm beeper.
the theory is to prevent any further water from entering the washer/ heater.
a pretty simple inexpensive device that also allows for shutting off the washing machine remotely. you can push the red/ close button and the valve will shut. great for a hard to reach stacking washer/ dryer.
green will open the valve
thought you guys might want to know about this.
here's a link that you can get more info from. never mind the pricing. they have contractor pricing for us