Reference ridge built into side of level allows easy alignment without a height offset Two precision vials - one level and a bulls-eye for plumb. Working Range: Up to 50' interior visible range. Line Accuracy:+/- 1/4 @ 50'. Laser Class: Class 2M/3R. Leveling Type: Manual, with base adjusting screw. Magnetic base. Special base leveling adjustment for maximum leveling accuracy, Manufacturer: Stanley