Dual Chamber Design increases level durability, ensuring accuracy over time, and resists twisting 2X more than traditional I-Beams. Plumb Site® offers dual-sided, undistorted viewing in the plumb position and easy, more accurate plumb readings. MagnaVials™ and wide top read window for easy, accurate readings. Rare earth magnets are 5X stronger than strip magnets and allow for easy hands-free steel construction work.