The Starrett 98-12 precision machinists' level is a 12" long spirit level with a graduated main vial that has a sensitivity of 0.42 mm/m or 80 to 90 seconds for determining horizontal plane, a cross-test vial that enables simultaneous leveling in two directions, and a plumb vial for determining vertical plane. The main vial is adjustable to a positive setting for accurate results, is made of ground glass vial that resists scratching to provide clear readings, and is housed in a brass tube with a friction-fit closing to resist breakage. A V-shaped groove along the base provides reliable seating when leveling round items such as pipe, conduit, and shafts. The level has a cast iron base for durability. Levels are used in the building trades, engineering, surveying, and metalworking, among other applications.

Levels are instruments that are used to determine the true horizontal or vertical plane of a surface. The most common type of level is the spirit level, or bubble level. Spirit levels have a liquid-filled, bowed tube (also called a vial) with a bubble that moves when slight adjustments are made to the level. When the bubble settles between marked points on the vial, it indicates that a surface is horizontally or vertically straight. Levels can have one or more vials to determine the horizontal plane, the vertical plane, or various points between, such as a 45-degree angle, simultaneously. Some levels include a laser line indicator that projects a horizontal or vertical beam on a surface. Bullseye levels, or surface levels, are circular, flat-bottomed spirit levels that determine whether a surface plane is level. Machinists' levels are made of metal and have surfaces designed specifically for rugged use in a machine shop or tool room. Levels can range from highly-complex and accurate machines, such as those used in the surveying and construction industry, to precision instruments used in carpentry and other building trades, to simple, pocket-sized devices for do-it-yourself projects.

The L.S. Starrett Company manufactures precision measuring tools, metrology and testing equipment, and saw blade products. The company, founded in 1880, is headquartered in Athol, MA.