The Fowler 53-422-048 Precision Spirit Level is a 5-7/8" x 5-7/8" level with two magnetic measuring bases for determining horizontal and vertical plane of cylinders and surfaces, and a main vial with a sensitivity of 0.2 mm/m (0.0002"/10") or 4 seconds for precise readings. The main vial is set into a steel tube to resist breakage, can be adjusted into the body of the level with a fine thread and screw calibration mechanism for maintaining accurate readings, and can be viewed from the side and the top. A small vial atop the frame allows coarse roll measurements. Both vials are made of glass to resist scratching and provide clear readings. The magnetic measuring bases adhere to metal surfaces and have V-shaped grooves that provide reliable seating when leveling round items such as pipe, conduit, and shafts. An insulated handle prevents transmission of heat from the operator's hand to maintain accurate readings. The level has a cast iron frame for durability and includes a fitted wooden case for storage. It is 150 x 150 x 6 mm/5-7/8 x 1-9/16 x 5-7/8 inches (H x W x D, where H is height, the vertical distance from the lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back). 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 Fred V. Fowler Company manufactures inspection and measurement instruments such as electronic indicators, calipers, bore gages, and digital scales. The company, founded in 1946, is headquartered in Newton, MA.