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. Overmolded rubber end caps provide shock-absorption, and are removable for accurate leveling into corners. Thick-walled high-grade aluminum frame provides extreme durability.