Medically reviewed by Dr Sin Yong · Last reviewed · 8 min read
Published 9 October 2026 · Reviewed by Dr Sin Yong
Scarlet, made by Viol (also the maker of Sylfirm X), and Secret RF, made by ILOODA, are both Korean fractional microneedle RF systems; Scarlet files gold-plated needles, and the Secret DUO lists gold-plated cartridges. The comparison below sets out what each filed with the US FDA.
Short answerBoth are bipolar microneedle RF systems with depth ranges of 0.5 to 3.5 mm, and both use gold-plated needles or cartridges. Scarlet SRF filed 0.25 mm depth steps; the newer Scarlet Pro files 0.1 mm steps with insulated and non-insulated 25- and 49-pin tips. Secret RF files 2 MHz with 0.1 mm steps, and the Secret DUO adds a 1540 nm fractional laser. Neither is shown to outperform the other.
Both 0.5–3.5 mm; Scarlet SRF 0.25 mm steps, Scarlet Pro and Secret RF 0.1 mm steps
Evidence
Scarlet: active acne with isotretinoin, n=40 (Hasan 2023). Secret RF: active acne RCT, n=25 (Kwon 2018)
Used here
Secret DUO, by Dr Sin Yong
Why this site compares devices against Secret RF. Dr Sin Yong is a global Key Opinion Leader for ILOODA’s Secret RF platform and performs RF microneedling personally on the Secret DUO. He has been invited by the manufacturer to share his clinical expertise with doctors internationally. That is a disclosed relationship, so the comparisons on this site stick to what each manufacturer has filed with the US FDA and what published studies measured, and do not rank one device above another.
Secret RF and Scarlet SRF compared from their FDA 510(k) summaries
Secret RF / Secret DUO (used here)
Scarlet SRF
Maker
ILOODA Co., Ltd., Korea
Viol Co., Ltd., Korea
RF type and frequency
Bipolar, 2 MHz
Bipolar; frequency not stated in the summaries reviewed
Needles
25- and 64-pin; DUO 25PIN-S, 1PIN, 4PIN gold-plated cartridges
Gold-plated surgical stainless steel; Scarlet Pro insulated and non-insulated 25/49-pin tips
Depth range
0.5–3.5 mm, 0.1 mm steps
0.5–3.5 mm (SRF 0.25 mm steps; Pro 0.1 mm steps)
FDA 510(k)
K170325 (2017); DUO K202043 (2021)
K180872 (2018); Scarlet Pro K253859 (2026)
Published studies found
Split-face RCT in active acne, n=25 (Kwon 2018; device named in a later review)
Microneedle RF plus isotretinoin vs isotretinoin alone, n=40 (Hasan 2023)
At this practice
Performed by Dr Sin Yong
Not offered here
RF microneedling places heat inside the dermis at a depth the doctor sets; the surface is spared when insulated needles are used.
Are Scarlet and Secret RF essentially the same?
They are close relatives in engineering: both Korean, both bipolar, both offering gold-plated needles or cartridges, with similar depth ranges. Scarlet’s newer Pro version adds a choice of insulated and non-insulated tips and finer depth steps, which brings it closer still. The Secret DUO’s distinguishing feature is the 1540 nm non-ablative fractional laser on the same console, which allows a needle-free fractional pass alongside RF microneedling in one visit.
What is the evidence for each?
For Scarlet, a trial of 40 patients with active acne compared microneedle RF plus isotretinoin with isotretinoin alone (Hasan, Postepy Dermatol Alergol 2023). For Secret RF, a split-face randomised trial of 25 Korean patients with acne found greater improvement with microneedle fractional RF than with a 1450 nm diode laser at 12 weeks (Kwon, JEADV 2018). Active acne is usually settled before needling scars; these studies looked at acne itself rather than established scarring.
Scar type, depth and skin type decide the plan, whichever device is used.
Which one should you choose?
Choose the doctor and the plan rather than the brand. Both devices deliver fractional microneedle radiofrequency; neither has been shown in a head-to-head trial to outperform the other. Ask which tip will be used, whether its needles are insulated, what depth is planned for each area and why, how energy will be set for your skin type, and who sets those parameters. Ask what RF microneedling will not help, and what would be done for that instead. A tethered scar needs subcision; pigment needs a different tool entirely.
Only the Secret DUO is used at this practice. Dr Sin Yong examines the skin, performs the treatment himself and sets out the plan and fee in writing; how fees are quoted explains why fees are not published.
Frequently Asked Questions
Neither has been shown to outperform the other. Both are bipolar with gold-plated needles and 0.5–3.5 mm depth; Scarlet Pro adds insulated and non-insulated tips, and the Secret DUO adds a 1540 nm fractional laser.
Viol Co., Ltd. of Korea, which also makes Sylfirm X. Scarlet SRF was FDA-cleared in 2018 (K180872) and Scarlet Pro in 2026 (K253859).
No. RF microneedling here is performed on the Secret DUO. Dr Sin Yong is a global Key Opinion Leader for the Secret RF platform.
References
US FDA 510(k) summary K170325 — Secret RF (ILOODA Co., Ltd.), 2017: bipolar 2 MHz, needle depth 0.5–3.5 mm in 0.1 mm steps. source
US FDA 510(k) summary K202043 — Secret DUO (ILOODA Co., Ltd.), 2021. source
US FDA 510(k) summary K180872 — Scarlet SRF (Viol Co., Ltd.), 2018: bipolar; gold-plated needles; depth 0.5–3.5 mm in 0.25 mm steps. source
US FDA 510(k) summary K253859 — Scarlet Pro (Viol Co., Ltd.), 2026: insulated and non-insulated 25- and 49-pin tips; depth 0.5–3.5 mm in 0.1 mm steps. source
Hasan IA, et al. Fractional microneedle RF plus isotretinoin versus isotretinoin alone in active acne (n=40). Postepy Dermatol Alergol. 2023. doi:10.5114/ada.2022.124109 (PMID 36909913). source
Kwon HH, et al. Microneedle fractional radiofrequency in acne: a split-face randomised trial versus 1450 nm diode laser in Korean patients. J Eur Acad Dermatol Venereol. 2018. doi:10.1111/jdv.14714 (PMID 29178495). source
Kumar N, et al. Fractional microneedle radiofrequency: a systematic review of 41 studies with device-level tables. Aesthetic Plast Surg. 2026. doi:10.1007/s00266-026-05834-y (PMID 42047762). source
