What you ended up buying was a combo thermometer and humidity meter, as EBCornell said. The unit you got is more for putting on the wall of your greenhouse, to monitor conditions for optimal growing. Unfortunately it has nothing to do with measuring alcohol or sugar. On the bright side, I'm sure that if you use it in the area/room that you're going to be doing your brewing in, it certainly won't hurt, as it would give you a good handle on the external conditions and variables that may effect your mead. ;D
