Dual chamber design increases level durability, ensuring accuracy over time, and resists twisting 2 times more than traditional I-beam levels. Plumb Site offers dual-sided, undistorted viewing in the plumb position and easy, more accurate plumb readings. MagnaVial and wide top read window supply easy, accurate readings. Other features include rare earth magnets and overmolded rubber end caps. Thick-walled high-grade aluminum frame provides extreme durability.