Commonly though wrongly called a transit, a builder’s level rotates only horizontally (a transit rotates both horizontally and vertically). Jim Anderson, Littleton, Colorado, framing contractor and author, says that looking through the level is like looking through a rifle scope, crosshairs and all. Properly set up, the magnification is great enough to read a tape measure held 100 ft. or more away.
In this video, Jim demonstrates the proper way to set up the level and explains what the measurements signify.
For more on framing techniques, read Jim’s article, Mudsills: Where the Framing Meets the Foundation.