The Irwin 1550 Magnetic I-Beam Level (48in) has a Dual Chamber Design that increases level durability, ensuring accuracy over time and resists twisting 2X more than traditional I-Beams. MagnaVials™ and wide top read window for easy, accurate readings. The rare earth magnets are 5X stronger than strip magnets and allow for easy hands-free steel construction work, which the end user will come to appreciate.