This Spirit Level is a Bubble Level, Surface Level, Horizontal Level, Vertical Level (plumb) and a Bulls Eye Level. Bubbles measure angles less than 10° giving high precision. Functions upside-down ideal for ceiling work. Astronomy Mode turns the screens brightness down and goes red so you don't lose your night vision. Includes a Compass too.   Great for levelling pictures, shelves, telescopes and building work. Also useful to carpenters, stonemasons, bricklayers, other building trades workers,