The FacialDefy 5.0 requires **water-based ultrasound/conductive gel** during treatment. Apply a generous layer of gel to the treatment area before use. The gel helps transmit ultrasound energy properly and ensures good contact between the cartridge and your skin. The machine comes with the treatment handles and cartridges, but **gel is not listed as included** and may need to be purchased separately. Please note that this is a professional HIFU device, so proper training is recommended before use.