What is the difference between Booster 1.5mm and Ultra F 4.5mm

The Booster 1.5mm cartridge delivers energy to the upper dermis for texture, fine lines, and tone. The Ultra F 4.5mm cartridge reaches the SMAS layer — the foundational tissue addressed in surgical facelifts — for deeper lifting and jawline definition. Shrink has 9 cartridge types spanning 1.5–9.0mm (including 6.0 and 9.0mm for body), and your surgeon combines them based on your anatomy and goals. Treatments can run in Normal mode or MP (Micro & Macro Pulsed) mode depending on the target layer.