InMode Forma vs MiniFX: What 50W vs 25W Means in the FDA Filing
Same table, two different wattages
The comparison table for non-invasive applicators in FDA 510(k) K210492 lists, handpiece by handpiece, the maximum radiofrequency output each one draws when clipped onto an InMode console. Forma (Plus) and Plus are rated at 50W, BodyFX at 50W, WMface at 65W, and MiniFX at 25W. The console itself tops out at 65W, and every applicator shares the same 1MHz ±2% frequency.
MiniFX’s own standalone clearance, K160329, doesn’t stop at a ceiling. It gives a full output range of 10W to 25W and specifies a maximum skin-surface temperature of 41°C ±2°C. The same device’s numbers show up in two different shapes depending on which filing you’re reading.
Even within the Forma line, output isn’t a single figure. The bench-testing section of K210492 records the i-Forma applicator emitting up to 12W and raising tissue temperature to 42°C. Sharing the Forma name doesn’t mean sharing a wattage.
The table also carries the console’s physical specs: 36.5cm wide, 39.3cm deep, 111cm tall, weighing 20.0kg, running on 100-240VAC. The predicate device, the InMode RF multi-system, lists the same 65W output but a weight of 32.0kg — so what changed in this clearance wasn’t the power ceiling, it was the size and the weight.
When a device labeled non-thermal holds steady at 41°C
The manufacturer’s product page introduces Forma and Plus as thermal technology, delivering bipolar RF into the dermal and subcutaneous layers. The same page describes a built-in thermistor that reads skin temperature 1,000 times per second to reach a clinically proven optimal temperature. What that optimal number actually is doesn’t appear anywhere on the page.
The language around MiniFX runs the other direction. The K160329 summary describes the handpiece as delivering non-thermal RF energy combined with mechanical vacuum massage to skin and subcutaneous fat. Yet the bench-results section of that same document states that all treatment modes reached a maximum of 41°C and held there for 20 minutes.
Separating the numbers by source clarifies what’s actually being said. The 1,000-times-per-second figure comes from the manufacturer’s marketing page; 41°C and 42°C come from test results in the clearance filings. Neither 510(k) summary registers a number for the thermistor’s sampling rate or the control loop’s response time.
Set side by side, the two descriptions push the question toward classification rather than physics: the filing calls MiniFX’s energy non-thermal while pinning its surface-temperature ceiling at 41°C ±2°C, and nowhere in the summary is there a definition connecting those two statements.
What’s inside the vacuum chamber
K160329 breaks the MiniFX handpiece down component by component: a vacuum pump, a vacuum chamber housing two bipolar electrodes, a pressure sensor, and a temperature sensor. The handpiece connects to the console through a 250cm cable, and energy delivery is triggered by a footswitch.
How it’s meant to be used is written in as a condition, not a suggestion. The summary states that MiniFX must be kept moving continuously across the treatment area for the non-thermal RF energy to distribute evenly. What happens to that distribution if the handpiece stops moving isn’t addressed.
Maintenance requirements simply carry over from the predicate device. MiniFX is a non-sterile, reusable instrument intended for use across multiple patients, with an expected handpiece lifespan of two years and materials confirmed biocompatible under ISO 10993-1. The cleaning instructions cite the predicate device’s own instructions, on the grounds that the materials and design are identical.
The list that gets one more line
The indications-for-use section of K210492 splits the non-invasive applicators into three groups. i-Forma, Forma (Plus), Plus (Plus Plus), and Plus90 are cleared for temporary relief of minor muscle pain and spasm and temporary improvement of local blood circulation — nothing more. Neither “lifting” nor “collagen” appears in that list.
The cellulite language sits in a separate group. Only BodyFX (WMBody) and MiniFX carry, in addition to those same three items, temporary reduction in the appearance of cellulite. Wrinkle language shows up in yet another line entirely, reserved for WMface’s clearance covering mild to moderate facial wrinkles.
The product codes follow the same boundaries. In K160329, MiniFX’s primary product code is PBX — electrosurgical cutting and coagulation device, under 21 CFR 878.4400 — with GEI as a secondary code. K210492’s system-level codes add ISA (therapeutic massager, 890.5660) and NUV (laser surgical instrument, 878.4810) on top. All of it is registered for prescription use.
Even within the same system, the fractional applicators get their own wording again. Morpheus8 and the Fractora 24-pin are cleared for electrocoagulation and hemostasis; the Fractora 60-pin is cleared for skin ablation and resurfacing. Above 62mJ per pin, use is restricted to skin types I through IV. Sharing a console doesn’t collapse these into one clearance statement.
The blanks both filings left
The clinical performance data field is marked not applicable in both K160329 and K210492. MiniFX’s substantial equivalence rests on a bench comparison showing matching RF output specifications against its predicate, BodyFX (K131362); neither filing includes animal testing data. The one human comparison on record — testing i-Forma’s thermal effect against the earlier Forma — sits inside K210492’s bench-testing section.
The standards editions the two filings cite are separated by a five-year gap. K160329 references the 1988 edition of IEC 60601-1 and the 2001 second edition of 60601-1-2. K210492 references the fourth edition of 60601-1-2 (2014) and the sixth edition of 60601-2-2 (2017). Even within the same manufacturer’s own product line, the baseline standard at the time of review isn’t constant.
The software item in K210492 is classified at the highest risk tier, “major.” The filing states the reason: a software defect or latent error could lead directly to serious injury to a patient or user. For a device where output and temperature are software-controlled, the scope of verification that grade demands is left in the summary as nothing more than a category name.
The unconfirmed numbers stay unconfirmed. Vacuum pressure intensity, electrode spacing, and the computation cycle for temperature feedback appear nowhere as figures in either summary, and a US clearance record says nothing about approval scope in other countries — the manufacturer’s own page notes that approved indications vary by country. The next document worth checking is the indication wording on a domestic approval certificate, and the point to watch is exactly where that wording departs from these two US records.
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Scope — This article explains devices and technology. It does not provide individual diagnosis or treatment advice.