Range, Each - These Proform digital bench top valve spring testers are the most accurate in determining measured valve spring pressure. They are manufactured from heavy-duty billet aluminum and can check valve springs from 1.5 in. diameters and 3 7/8 in. tall. The digital display reads in 1 lb. increments and has backlighting for easy identification. The Proform digital bench top valve spring testers also feature peak hold and automatic shutoff.