Spirit level or bubble level is an instrument designed to indicate whether a surface is level. Different types of spirit levels are used by carpenters, stone masons, bricklayers, etc. A traditional carpenter’s spirit level looks like a short plank of wood and often has a wide body to ensure both stability, and that the surface is being measured correctly. Embedded in the middle of the spirit level is a small window where the bubble and the tube are mounted. Two notches (or rings) designate where the bubble should be if the surface is level.