It means that Flow is approved for medical use and compliant with the strict European laws for medical devices. The CE certification ensures that: 1) Flow is based on scientific evidence, 2) the treatment reduces depressive symptoms and 3) the headset is safe to use.  As part of the certification process, third-party experts on brain stimulation have reviewed the scientific evidence proving that the technology used in the Flow headset is both safe and effective. Read more about the Science.