PLUMB-IT EXTENDIBLE LEVELS This innovative device has a primary function to save time and assure unparalleled precision in determining "plumb" and "level" when placing or erecting structural members. Interlocking triple anodized I-Beam design prevents damage from bending. You can use the Plumb-It Level on balloon, clip, rake and gable end walls, setting crowned form boards level end to end, also as a layout for stud height and stud location around existing duct work and other protrusions. Use Plumb-It as a general layout tool and to determine existing wall plumbness when remodeling. Precision milled Vials are fixed but replaceable and accurate to .057 degrees or 1/1000 of measured length.