The STANLEY STHT42496 24" Box Level (Non-Magnetic) features a center block vial for durability and precise accuracy. This level was designed with large 12mm tubular plumb vials for accuracy of 0.001"/in. It has enlarged vial housing for bright lit vials which help visibility, and also offers a MaxEdge bridged center vial which allows for a continuous marking surface and added durability. The shock-absorbing end caps are an added benefit for increased durability and longer life of your tool. Box Level