The IRWIN 2500 / 2550 Series Heavy Duty Box Beam Level - 48" Thick-walled high-grade aluminum frame provides extreme durability and resists jobsite wear and tear. Continuous Edge increases level durability ensuring accuracy over time, protects center vial, and allows for continuous scribing. Plumb Site® offers dual-sided, undistorted viewing in the plumb position and easy, more accurate plumb readings. Over-molded rubber end caps provide shock-absorption, protecting the level's accuracy upon impact, and are removable for accurate leveling into corners.