Block vials provide maximum accuracy of 0.0005 in/in (0.5mm/m). MaxEdge™ bridged center vial for continuous marking surface. Single-piece, aluminum box-beam structure for durability and accuracy. Rubber-gripped hand hole designed with comfort in mind. Shock-absorbing end caps hold up to heavy use. Rare earth magnets. Non-marring side bumpers helps prevent damage to finished surfaces.