Unlike most fitness products, inversion tables are not required to meet any mandatory structural or performance requirements. Only Teeter meets the NEW UL 1647 standard. Unlike previous UL certifications, the new standard is designed to test the unique function of the inversion table & simulate "real world" use, evaluating key safety factors such as: Cycle testing to a minimum of 30, 000 repetitions. Weight load testing to a minimum 400% safety factor (based on the maximum rated user weight) Ankle closure endurance testing to a minimum of 30, 000 repetitions Top-speed rotation testing at the maximum rated user weight to ensure integrity under extreme conditions.