Precision Machinists Level, 4", Starrett

This level has ground and graduated main vials. These vials are adjustable to a positive setting and are housed in a satin chrome brass tube with a friction-fit closing cover to prevent breakage.
Starrett catalog number 98-4.

The base of the level features an involute groove running the length of the base, which provides a reliable seat for round work such as pipes or shafting.

The main level vials have graduations that are approximately 0.015" per foot (1.25 mm per meter). There are three lines on each side of the bubble.

These are the finest levels available, used for precision work that is typically required in industry. They all have these features:

All level bases are made from the finest quality seasoned cast iron and are precision-machined on the reference surface. Nonmachined surfaces have an attractive, black wrinkle finish. An involute longitudinal groove between the bearing flats for accurate seating on round work. This groove has a special involute design, permitting better centering and greater capacity to handle larger rounds. Groove and bearing flats are machined together for maximum accuracy.