We are proud to say that the BIG RED series spirit levels are the most accurate spirit levels in the world. With a maximum measurement tolerance of 0.0003 in./in. (0.3 mm/m, 0.017 Degrees) for standard measurements and 0.0005 in./in. (0.5 mm/m, 0.029 Degrees) for inverted measurements, there's no competition when it comes to choosing a tool for your next important job.