Stanley 43-672 72-Inch FatMax Xtreme Box Beam Level Durable Box-beam construction is up to 5-times stronger than other Stanley levels Stanley - Black & Decker Magnified center vial for improved visibility Machined leveling surfaces improves accuracy Limited lifetime warranty Durable Box-beam construction is up to 5-times stronger than other Stanley levels Block vials provide accuracy of 0.0005-inch-per-inch Magnified center vial for improved visibility Machined leveling surfaces improves accuracy Limited lifetime warranty