Smart rings / Comparison

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Health-tracking smart rings sold new in the US with their included charger. Payment-only rings, NFC rings, fitness bands, smartwatches and measured accuracy, sleep or battery rankings are outside this catalogue.

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Documented specifications and exact purchase packages
Compare the details	Circular Ring 2 Obsidian Black, buyer-selected size (US)
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US purchase package	Circular Ring 2; Obsidian Black; US size 6 to 14 chosen by the buyer with I know my size; no replica-ring sizing kit, extra charger case, extension cable or Circular+ Guarantee Product & sources Silver, Gold and Rose Gold are the other finishes. The store ships worldwide and states HSA/FSA eligibility in the US; the shipping origin is not stated. Circular does not publish a part number on the page read. Price, delivery and stock are not recorded. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Where to buy	Select: Circular Ring 2; Obsidian Black; US size 6 to 14 chosen by the buyer with I know my size; no replica-ring sizing kit, extra charger case, extension cable or Circular+ Guarantee View at Circular — Circular Ring 2 Obsidian Black, buyer-selected size (US); opens in a new tab The link may open several packages. Check current price and availability with the seller. Opens in a new tab.
Sizes and sizing kit The ring sizes the manufacturer lists for the US and how its sizing kit is offered. Smart ring sizes differ from jewelry sizes and between brands and generations. Use the maker's own sizer before choosing a size; the buyer selects the size for every package here.	US sizes 6 to 14. A replica-ring sizing kit is a separate checkout option; with a known size the ring ships straight away. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Ring weight The published weight of the ring, with the size basis where the manufacturer states it. Weight changes with size. A single figure without a size basis is not comparable with a range.	4 g; size basis not stated. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Width and thickness The published band width and thickness of the ring. Thickness can vary by size. These are body measurements, not a comfort or fit guarantee.	Width 7.8 mm; thickness 2.55 mm. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Materials and finishes The shell and inner-surface materials and the finishes listed for the US. Finishes can change the coating and the SKU. Scratch and allergy statements are manufacturer claims.	Titanium body with a PVD finish and a hypoallergenic interior; finishes Silver, Obsidian Black, Gold and Rose Gold. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Longest stated ring battery life The upper end of the manufacturer's battery-life claim for the ring on one charge, without a charging case. A maker estimate under its own sizes and settings, not a measured result. Read the conditions field for the size basis and the features that shorten it.	8 daysAbout 8 days in power mode. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Battery claim conditions The size basis, modes and settings behind the battery claim, including any case-assisted figure. Smaller rings usually carry smaller batteries. Days with a charging case include recharges from the case and are not a ring battery figure.	About 8 days in power mode and about 4 to 5 days in performance mode with high-frequency measurement; no size basis is stated.The page gives both around five days and four to five days for performance mode. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Charger and charging The charger type supplied, whether it carries its own battery, and the stated charging time. Some chargers are size-specific and some cases are not sold separately. A portable case with a battery is different from a dock that needs a cable.	Wireless charging case with a USB-C cable for the case; about 30 minutes to full.Whether the case has its own battery is not stated. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Water rating The water resistance as the manufacturer states it, in ATM, IP or meter terms with any conditions. A 100 m figure is not a diving rating. IP68 conditions are set by the maker. Follow the stated limits for submersion, diving and heat.	IP68; Circular says showers, swimming and daily wear are fine.No depth or duration is stated for the IP68 rating. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Sensors listed The sensor hardware the manufacturer lists, or the signals it says the ring measures where no hardware is listed. A listed sensor is not a validated measurement. Which metrics appear can depend on the app, a plan or an add-on.	ECG, PPG, temperature sensor and 3-axis accelerometer. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Blood oxygen documented Whether the manufacturer documents blood oxygen (SpO2) readings for this ring. Often measured only during sleep and sometimes off by default. It is a wellness reading unless the maker states a regulatory clearance.	YesBlood oxygen is listed among the core features. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Works with iPhone Whether the manufacturer states the ring's app works with iPhone, or states a requirement that excludes it. The manufacturer's compatibility statement, not a tested result. Minimum iOS versions are in the requirements field where published.	YesCompatibility is stated as iOS and Android; no minimum version is given. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Works with Android Whether the manufacturer states the ring's app works with Android phones. Some rings document only one brand of Android phone, or limit features on others. Read the requirements field.	YesCompatibility is stated as iOS and Android; no minimum version is given. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Phone and app requirements The stated phone platforms, minimum versions, apps and accounts the ring needs. Where two manufacturer statements differ, both are recorded. An account is not a subscription, but the ring may not work without it.	Circular app on iOS or Android; minimum phone versions not stated on the page read. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Core features without a subscription Whether the manufacturer states that the ring's core health features are available without a paid plan. False means the maker limits most insights to paid members. True can still leave optional paid add-ons, listed in the terms field.	YesCircular states there is no mandatory subscription. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Subscription terms as stated What the manufacturer says works with and without a paid plan, and any optional paid add-ons. Prices are not recorded. A trial month included with a ring is not a permanent entitlement. Plans and their contents can change after purchase.	No mandatory subscription: ECG, blood pressure, sleep, energy, vital alerts, cycle tracking, HRV, temperature, blood oxygen and live measurement are included. A small number of advanced screens are premium and unlocked with coins earned by wearing the ring. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Wellness or regulatory wording The manufacturer's own wording on whether the ring is a wellness product or holds a regulatory clearance. Quoted as published. Features such as ECG, apnea or blood pressure trends are not a diagnosis unless the maker states a clearance for that feature.	Circular describes clinical-grade ECG and AFib detection but states no FDA or other regulatory clearance on the page read. It calls the blood pressure reading a wellness estimate, not a diagnosis, needing cuff calibration every 30 days. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
In the box Items the manufacturer lists in the exact US package. Sizing kits, spare charging cases, extended protection and paid plans are separate unless the package lists them.	Circular Ring 2, wireless charging case, USB-C cable and cleaning cloth; app access for iOS and Android with a digital user guide. Source · 2026-10-21 Circular: Circular Ring 2 store pageChecked 2026-10-21. We reviewed the official page text on the check date. Checkout options were not verified.
Questions to check before buying	The ECG and AFib claims carry no stated regulatory clearance on the page read; confirm the status with Circular before relying on them. The 4 g weight and battery figures have no size basis, and the IP68 rating has no published depth or duration. Circular also runs a Ring 3 waitlist.

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