IRWIN Tools STRAIT-LINE Magnetic Box Beam Level, 72-inch (2035105) Designed for optimal accuracy and durability. Made of premium-grade aluminum for unrivaled strength. Resists warping, twisting, and bending. Guaranteed to remain accurate, even after a 2-story drop or 50-degree temperature change. Vials never break, fade, fog, leak or develop static charge. Luminous backing means easier readouts in low light. Rare earth magnets are 5 times stronger than strip magnets and allow for easy, hands-free steel construction work.