Trusculpt 3D requires the operator to control the energy pulse and to move the handpiece to keep the energy even and to prevent heating the skin beyond what is safe. In Trusculpt ID, the heating RF pads are placed on the skin and don't move. The pads have sensors in the them to control energy delivery and to ensure the skin isn't heated beyond the safe temperature zones. The procedure time is general less with the ID than the 3D for the same amount of area treated.
Thank you for your question, TruSculpt iD is the newest version of truScuplt by Cutera. These devices use RF to therapeutically heat fat to destruction, where it is then removed by the body naturally overtime. There is no downtime and no anesthesia required. Treatments take as little as 15 mins with a 24% fat reduction and beneficial skin tightening. The 3D version is still available with the iD to treat certain areas. Best, Scott Grevey, M.D.