WALL LEVEL. The turquoise wall level retails for $300 or so dollars. It is self leveling (when placed on a level to (5 deg) from level surface). Displays two red lines on the nearest wall surface. One Plumb (vertical) line and one Horizontal (level) line, these two lines intersect at 90deg (naturally). By rotating the level unit on the same spot you can draw a level line around the entire room. Now if you are an old codger like me you would have learnt how to do this with a water level. Believe me, this is far simpler and just as accurate in a bathroom. Can not be used in direct sunlight.