Unlike most fitness products, inversion tables are not required to meet any mandatory structural or performance requirements. Teeter backs our claims of quality by listing our manual inversion tables to UL 1647, a specification written by Underwriters Laboratories, the foremost product safety certification organization. The spec includes requirements for inversion equipment in regards to stability, reliable function, rotation control, and other key safety factors. Teeter inversion tables are also classified to UL 60601-1, a medical grade standard.