HIFU is commonly used to improve sagging skin on the face and neck, stimulating collagen production and firming and lifting the neck contour. It can also improve double chins and neck wrinkles, but results vary from person to person. Procedure Precautions: Avoid the thyroid gland: Do not perform procedures on the center of the neck or the Adam's apple area to avoid damaging the thyroid gland and laryngeal tissue. Energy Setting: The skin on the neck is thinner, so use lower energy and an appropriate probe depth (generally 1.5mm or 3.0mm). Technique: Follow the jawline and both sides of the neck, avoiding compression of the carotid artery.