The Stanley Box Beam Level features a center block vial for durability and precise measurement with 0.0005 in./in. surface accuracy. The durable box frame and shock absorbing end caps allow this level to stay accurate in the toughest of conditions. MaxEdge bridged center vial and mitered surfaces allows for a precise continuous marking surface. Combined with 0.001 in./in. 12mm easy to read tubular plumb vials, the Stanley Box Beam Level is designed to stay reliable and accurate for any job.