Bora 610040 16-Inch Professional Box Frame Spirit Level, 2 Vial Proprietary high tensile internal reinforcement bars set in epoxy resin guarantee the level will stay true. U.V. and scratch resistant acrylic vials Aircraft grade structural alloy body extruded to exact tolerances for accuracy and durability State of the art CCS precision vial setting assures its lifetime accuracy. Easy to read magnified center vial and slip resistant wall pads