HIFU cartridge depths explained: 1.5, 3.0, 4.5, 8 and 13 mm
A HIFU machine is only as flexible as its cartridges. Each depth is designed for a different layer and a different area.
Published 10 November 2026 · Lazenix
How HIFU works
HIFU stands for high-intensity focused ultrasound. The handpiece focuses ultrasound at a set depth under the skin. At the focal point the tissue is heated to approximately 60–70°C within milliseconds, which creates small thermal points. The skin's natural response then supports collagen remodelling. The surface of the skin is not the target: the energy converges below it.
The cartridge decides how deep the focal point sits. That is why a HIFU system comes with several cartridges and why choosing the right one for each area matters.
What each depth is for
| Cartridge | Layer | Typical areas |
|---|---|---|
| 1.5 mm | Superficial dermis | Fine lines, forehead, skin texture |
| 3.0 mm | Deeper dermis | Cheeks, lower face, mild neck laxity |
| 4.5 mm | SMAS layer | Structural lifting, jawline, submental area |
| 8.0 mm | Subcutaneous tissue (body) | Upper arms, abdomen, flanks, thighs |
| 13 mm | Deeper subcutaneous tissue (body) | Abdomen, flanks, buttocks, thighs |
These are the five standard cartridges of the EternaLift Elite Pro. The depths and uses come from its operator manual. Tissue thickness varies between people and between areas, so the practitioner assesses each client before choosing a cartridge.
Why 4.5 mm gets the attention
The SMAS is the supporting layer beneath the skin and fat of the face. It sits at approximately 4.5 mm in many facial areas, which is why the 4.5 mm cartridge is used for structural lifting. It must not be used over thin tissue or directly over bone, which is one reason proper training matters.
Layered treatments
Practitioners often combine depths in one session, for example 4.5 mm and 3.0 mm on the lower face, treating the deepest layer first. A system with a wider range of cartridges gives more room to tailor a treatment to the client.
What to ask before you buy
- Which cartridges are included as standard? On the EternaLift Elite Pro: 1.5, 3.0, 4.5, 8.0 and 13 mm.
- How many shots does a cartridge deliver? 10,000 on the EternaLift Elite Pro, with a counter on screen.
- How many lines per pulse? Multi-row delivery places several treatment lines at once, which shortens sessions.
- Is there a handpiece for delicate areas? The Ring Focus handpiece combines focused RF with micro-focused ultrasound for smaller areas of the face.
Results from HIFU develop gradually. The manual describes the main results appearing over 8–12 weeks, with collagen remodelling continuing for up to 3–6 months.
Slide through all five depths and see which layer each one reaches.
Open the depth explorerThis article is general information for clinic owners and practitioners. It is not medical, legal or financial advice. Device figures are taken from the operator manuals and may vary with configuration.