STABILA magnetic levels are the most trusted levels for commercial carpentry. All STABILA tools are factory tested and durable; built to handle real world job site conditions while providing craftsmen with the dependability and consistent accuracy they expect and deserve. All accuracy tolerances stated by STABILA are absolute values. STABILA products will never perform below their stated accuracy. STABILA levels will maintain their stated accuracy for life. If they don't, you will be given a new level. Protect your investment with a case.