XERF vs Thermage, Ultherapy, ONDA and Density: What Is the Difference? (Gangnam, Seoul)

Quick answer: XERF, Thermage FLX and Density all heat the skin with radiofrequency (RF). Ultherapy uses ultrasound, and ONDA uses microwaves. Within the RF group, what sets XERF apart is that it uses two frequencies, 2MHz and 6.78MHz. There are no head-to-head trials showing one is better, so at REPIC Clinic in Gangnam, Seoul, we look at which layer the sagging comes from before we look at the device.

I'm Dr. Jay (Yongheon Ha), a doctor at REPIC Clinic in Gangnam. Since XERF came out, "How is it different from Thermage?" has become one of the most common questions I get. Plenty of people lump ONDA and Ultherapy into the same question. Five names, but only three types of energy: radiofrequency, ultrasound and microwave. Get those three straight and the choice gets much easier.

XERF vs Thermage FLX: what's the difference?

Both are monopolar RF, with a different frequency setup. Thermage FLX uses one frequency, 6.78MHz; XERF uses two, 2MHz and 6.78MHz. When the US FDA cleared XERF in August 2025, the device it was compared against was Thermage FLX. That tells you how close the underlying principle is.

So is XERF better than Thermage, or less painful? There's no data that answers that yet. No trial has compared the two devices in the same patients, and the FDA clearance showed equivalence with tissue temperature testing, not human trials. XERF's manufacturer presents it as a treatment done without numbing cream, but that hasn't been confirmed in a comparison trial either. When choosing between them, I decide how many shots each area needs, and at what depth, before I think about the device name.

How is Ultherapy different?

Ultherapy isn't RF at all. It's micro-focused ultrasound. Where RF heats broadly, ultrasound concentrates heat at a single point to target a deeper layer. Think of RF as an electric blanket warming the whole bed, and ultrasound as a magnifying glass focusing light onto one spot. If firmness and fine lines at the skin surface are the concern, I look at RF first. If it's sagging in a deeper layer, like along the jawline, I look at Ultherapy first. Some packages combine the two.

Is ONDA also radiofrequency?

No. ONDA uses 2.45GHz microwaves, a different kind of energy from RF. I consider ONDA separately for people whose lower face looks heavy because of fat thickness. For people with thin, loosened skin, I don't recommend ONDA on its own. That's why some of our packages pair it with XERF or Thermage.

How is Density different?

Density is also a 6.78MHz RF device, using both monopolar and bipolar tips. Being in the same RF group as XERF, the two overlap in what they do, and no comparison trial shows one outperforming the other. At REPIC Clinic, we help you choose based on tip setup, price and what it's combined with.

So which one should I get first?

The layer the sagging comes from decides it. If the skin itself has thinned and loosened, RF. If weight has dropped from a deeper layer, Ultherapy. If fat thickness is the issue, ONDA. If the face has hollowed from lost volume, none of these five is the answer; filler or a collagen booster comes first. Real faces usually mix two or three of these, which is why our packages include XERF with ONDA, and XERF with Ultherapy.

For the eye area, Eye XERF or Eye Thermage?

Both are RF treatments for the eye area. The difference is the frequency setup described above, and no study has compared the two around the eyes. Around the eyes, I look at the cause before the device. Is eyelid skin loosening and folding, or does the area look droopy because the upper lid or under-eye has hollowed? If it's hollowing, RF won't fill it. That's the case our Eye XERF + Re2O package is designed for.

Can I combine several devices?

Yes. Our packages include XERF with ONDA, and XERF with Ultherapy Prime. Different energy types do different jobs, so for a face where sagging has two or more causes, I think it's better to plan across devices than to keep adding shots on one. Whether you get them on the same day or on separate days is decided at the exam, based on your skin and your schedule. If you have a flight home, tell us your departure date at the consultation and we'll fit the dates around it.

Who shouldn't get these treatments?

If you have an implanted electronic device such as a pacemaker, a metal implant that could interfere with the energy, or an active infection, tell us beforehand. The US XERF trial excluded these people too. We don't treat during pregnancy or breastfeeding. Every one of these devices delivers heat, so redness and swelling can occur. And if you're expecting a thread-lift-level change from one session, I don't recommend any of these five, because none of them is that kind of treatment.

How do the prices compare? (November 2026)

Each device counts shots and energy in different units, so don't compare shot counts across devices. Below are representative REPIC Clinic Gangnam options, all VAT not included. XERF is available at REPIC Clinic Gangnam from November 17, 2026, and the XERF prices below are launch promotion prices valid from November 23 to December 31, 2026 (advance booking available; you can't request a specific doctor).

Some bundles exist only during the promotion, such as XERF 300 shots + ONDA 80KJ for 1,990,000 KRW. Full options are on the XERF, Thermage FLX, Ultherapy Prime, Density and ONDA pages and our price list.

How we do it at REPIC

We don't pick the device first. At the doctor's consultation, we work out whether the skin has loosened, a deeper layer has sagged, volume has been lost, or fat thickness is the cause. Then we set the device, shot count and how it's split across areas, and if two or more causes are mixed, we plan a combination. After treatment, we check your progress and set the next step again.

Related reading

• XERF lifting: who it suits and how many shots you need
• Thermage vs Ultherapy: differences and how to choose
• Ultherapy lifting: shots, pain and cost

Booking and questions: book online

This article is general information and does not replace a medical consultation. Results vary from person to person.