Ask most suppliers what the D stands for and you will get an answer about generations, dimensions or technology. It stands for none of those. D is a count of treatment depths — how many distinct depth cartridges the machine is designed to work with.
That was a genuinely useful number once, because a machine that can work at more depths can be used across more areas. Then it became a marketing number, and it stopped matching the hardware.
D means depths — nothing else
Each HIFU cartridge is built to focus at a particular depth. A machine that supports cartridges at five different depths is a five-depth machine. That is where 3D, 5D, 7D came from — the count of depths available.
So the honest way to read any D number is as a claim about depths. Which means it is checkable, because you can simply count the depth cartridges the machine actually comes with.
- The number should equal the count of distinct depths the machine works at.
- It is not a generation number, a technology version, or a quality rating.
- It says nothing about how good any individual cartridge is.
- And crucially, it is not audited by anyone — so nothing stops a supplier printing a larger number than the machine supports.
How the number stopped matching the machine
Because nobody audits the label, the number inflated. This is now routine rather than exceptional, and it is easy to catch if you know to look.
The test takes one message. Ask: “Please list the depth cartridges this machine ships with.” Then count them. If the count does not match the number on the box, you now know two things — the real specification of the machine, and how this supplier describes their products.
| What the box says | What to ask | What you may find |
|---|---|---|
| 22D | List the depth cartridges supplied | 5 depths — a 5D machine |
| 12D | List the depth cartridges supplied | Often far fewer depths, with the count made up of duplicates |
| 7D | List the depth cartridges supplied | Sometimes accurate — count and confirm rather than assume either way |
None of this requires an argument with the supplier. You are asking for a list, which is a reasonable request, and the list settles it.
Why more cartridges is often worse, not better
This is the part almost nobody tells a buyer, and it matters more than the label. A higher cartridge count is not a better machine. Sometimes it is evidence of the opposite.
Because buyers have learned to count cartridges, some factories have responded in the obvious way: reduce the shots and the power output per cartridge, and increase how many cartridges are supplied. The headline number goes up. Every individual cartridge gets weaker and shorter-lived.
- Fewer shots per cartridge means you replace them sooner, so your running cost rises even though the machine looked more generous.
- Lower power output per cartridge means each cartridge is doing less work than a properly specified one.
- A bigger count hides both, because the count is the only number most buyers check.
So the number of cartridges is not the specification. The specification is: how many distinct depths, and for each cartridge, how many shots and how much power. Those three figures describe the machine. The D number describes the marketing.
What to ask for instead
Send this to every supplier on your shortlist, identically worded. The replies become comparable in a way that quotations never are.
- Exact model number and manufacturer — not the marketing name
- The list of depth cartridges supplied, by stated depth — then count them against the D number on the box
- How many distinct depths that list actually represents, once duplicates are excluded
- Rated shots per cartridge, for each cartridge type
- Power / output rating per cartridge, for each cartridge type
- Replacement price of each cartridge type, today, in writing
- Number of handpieces included, and whether they are warranty-covered
- What the written warranty covers and excludes, part by part (see warranty wording)
- Who repairs it, where, and who pays freight in each direction
- What training is included, for how many staff, and what further training costs
- Electrical requirement and physical footprint
- Which certificate applies to this exact model, with a copy attached
Rows two to five are the ones that expose an inflated label and a diluted cartridge set. A supplier who answers all four in writing is being straight with you, whatever their price. Our buying checklist is the same list formatted to take into a meeting.
A distinction that does matter: portable vs vertical
While the D number tells you little, machine format tells you something real, because it affects how you actually run the clinic.
| Format | Practical implication | Ask about |
|---|---|---|
| Portable / desktop | Moves between rooms, smaller footprint, easier for a single-room setup or a mobile service. | Whether the carry case is included; how the cartridges store and travel. |
| Vertical model (floor-standing) | Stays in a dedicated room, generally a larger screen and more physical presence in front of a client. | Whether the room's power supply and floor space suit a full-height unit. |
Neither is better. One suits a clinic with one treatment room and a mobile practitioner; a vertical model suits a dedicated aesthetics room where the machine's presence is part of the pitch. Decide this from how you work, then compare within the format you chose.
Frequently Asked Questions
What does the D in HIFU actually stand for?
The number of treatment depths the machine offers — how many distinct depth cartridges it works with. It is not a generation, a dimension or a technology version, and it says nothing about the quality of any individual cartridge.
Is a 22D HIFU machine better than a 7D?
Not necessarily, and often not. Ask both suppliers to list the depth cartridges actually supplied. A machine marketed as 22D may ship with only five depth cartridges, which makes it a 5D machine with a larger number printed on it. Count the list, not the label.
Is a machine with 12 cartridges better than one with 5?
No — and this is the trap. Some factories reduce the shots and the power output per cartridge and increase the quantity supplied, so the count goes up while each cartridge gets weaker. A good machine with five properly specified cartridges can be considerably better than a 12D shipping many inferior ones.
What should I actually ask on the first call?
Three things: the list of depth cartridges supplied, the rated shots per cartridge, and the power rating per cartridge. Then count the depths against the number on the box. How completely and how quickly that gets answered tells you most of what you need to know about the supplier.