Thank you for your question. The terms like 3D, 9D, and 11D HIFU are mainly marketing names and do not represent a universal industry standard. FREYARA HIFU models are classified by technology, cartridge options, treatment depths, and professional level: * FacialDefy 2.0: Portable HIFU for personal beauty care * FacialDefy 3.0 / 4.0: Advanced models with more functions and cartridge options * FacialDefy 5.0 / 6.0: Professional systems with upgraded HIFU + RF functions This FY18.0022US model is the US version and is compatible with US standard voltage. For the best choice, please select the model based on your intended use (home or professional salon).