Extra-sturdy box-section frame, enamel baked with epoxy-polyester coat that protects and makes washing down easy. Solid acrylic, shock-proof, non-fog vials fixed solidly with a permanent, fixed vial housing. Top read level (horizontal) vial features Nite-Glo liquid for enhanced visibility in poor light conditions. 1 plumb vial features Plumbsite window for accurate, quick and easy use by allowing user to read vial in both regular and front reading positions simultaneously to eliminate parallax error and enhance vertical vision field. 2 milled leveling surfaces for accuracy. Electronically calibrated and tested accuracy of 0.5mm/M, 0.029° . Features 2 Ergo-Grip non-slip handles for simple marking of readings.