Starrett 98-8 8" Precision Machinists' Level with Main and Cross-Test Vials 8" precision machinists' spirit level with a main vial and a cross-test vial for determining horizontal plane Graduated, ground glass main vial has a sensitivity of 0.42 mm/m or 80 to 90 seconds and is adjustable to a positive setting for accurate results Cross-test vial enables simultaneous leveling in two directions V-shaped groove along the base provides reliable seating when leveling round items Cast iron base for durability Cross test vial allows simultaneous leveling in both directions Ground and Graduated main vial Made from the finest quality seasoned cast iron Precision machined on the reference surface Nonmachined surfaces have black wrinkle finish