Levels may be encased in a horizontal bar analagous to a ruler, such as the carpenter's level. They can also be hung on string, to check that the string line is level. Some machines will have a level built in also, to ensure accurate level surfaces. | Levels may be encased in a horizontal bar analagous to a ruler, such as the carpenter's level. They can also be hung on string, to check that the string line is level. Some machines will have a level built in also, to ensure accurate level surfaces. |