http://www.defender.com/product.jsp?path=-1|51|2234261|2234262&id=2538376

On another BB the pro's and con's of such a device has been discussed. I have never seen such a seacock before browsing the Defender website of sales offerings but I'm sure Jon E has one. (grin).
Some of the questions raised were what happens on a failure? In what position does the seacock revert to when it loses power? Is there an override? Why would anyone invest in this?