Smart Rings / Renpho
Renpho LYNX Smart Ring (2025)
The friendliest returns and warranty in the category, wrapped around modest sensing.
Overall score 7.3/10
Pros
- + 18-month warranty and a 30-day money-back guarantee — the most forgiving terms in the category by a distance
- + Sizing kit ships in the box, so there is no one-to-two-week wait before the ring is dispatched
- + Syncs into Apple Health and Google Health Connect, so your history leaves the vendor app
- + $179.99 once, no subscription, no upsell tier
Cons
- − 5ATM/50m water rating is half what Oura, RingConn and Ultrahuman offer
- − No temperature sensor is listed in Renpho's US specification, so illness and cycle signals are weaker than rivals'
- − The 12-day battery claim carries no published conditions and outruns similarly-sized rivals — expect less
- − Live Science's reviewer concluded it is expensive for what it offers; the app is the least sophisticated of the mainstream options here
- − Stainless steel band under the titanium finish makes it heavier on the hand than a 2-3g RingConn
Renpho LYNX Smart Ring (2025) review: what the specs say
The friendliest returns and warranty in the category, wrapped around modest sensing. At $179.99, Renpho's 2025 model sits among the cheapest we cover — the smart Rings we compare run from $149.99 to $479. It scores 7.3/10 overall, calculated from published specifications across 8 categories rather than from a subjective impression.
Its strongest showing is Subscription Freedom at 9.5/10 — how much of the ring keeps working with no recurring payment — the category's defining trap. The weakest is App & Data at 5.5/10, which is the trade-off to weigh before buying: if that is the specification you care about most, one of the alternatives below will serve you better.
Worth knowing before you buy: 5ATM/50m water rating is half what Oura, RingConn and Ultrahuman offer; and no temperature sensor is listed in Renpho's US specification, so illness and cycle signals are weaker than rivals'. Every specification on this page comes from Renpho's own documentation or a verified retail listing — where a figure is not published, the table says so rather than estimating it.
Specifications and price last verified . Report an error
Full Specifications
| Battery Life (claimed) | 12 days |
| Battery, In Practice | Renpho claims 12 days on a single charge with more available from the case. That is a headline figure with no published conditions attached, and it sits above what comparably-sized rings from RingConn achieve, so treat it as a ceiling rather than a typical result. |
| Subscription | None. Renpho states no subscription fees are required for app connectivity and every tracked metric is included. |
| 3-Year Cost of Ownership | 179.99 $ |
| Sizes Offered | US 6-13, no half sizes |
| Sizing Kit | Included free in the box rather than shipped ahead — so the ring and the sizer arrive together, and a wrong size means an exchange rather than a delayed order. |
| Returns & Size Exchange | 30-day money-back guarantee, the most generous window here, backed by an 18-month warranty. |
| Measured vs Inferred | PPG optical sensing for heart rate and blood oxygen plus motion tracking. Stress and sleep scores are derived from those signals; Renpho does not publish a sampling rate, and there is no temperature sensor called out in its US specification. |
| FDA Clearance | None published. General wellness product. |
| Water Rating | 5ATM (50m) — half the rating Oura, RingConn and Ultrahuman claim |
| Phone Support | iOS and Android, with sync into Apple Health and Google Health Connect |
| Charger & Data Export | Charging case and USB cable both included. Export: data syncs out to Apple Health and Google Health Connect, so history is not trapped in Renpho's app the way it is with RingConn or Circular. |
| Connectivity | Bluetooth Low Energy (version not published by Renpho) |
| Material | Titanium alloy exterior over a stainless steel band |
| Warranty | 18 months |
Compare Renpho LYNX Smart Ring (2025) With
Cheaper Alternative
Amazfit Helio Ring (2024) — $149.99
Premium Alternative
RingConn Gen 2 Air (2025) — $199.00