Device hub · Fitness rings · Desk research
Circular Slim
Slim is the discontinued 2 g / 2.2 mm Circular: 5 days, 5 m / 30 min, vibration + tap button, free app on old OS floors.
Product images
Product photography stays on circular.xyz.
Credit: GadgetShowdown labeled placeholder (not a Circular asset). View official product image
Studio still only. Manufacturer press JPEGs are not hosted here. See the official product page for the real product photo.
In short
Slim is the discontinued 2 g / 2.2 mm Circular: 5 days, 5 m / 30 min, vibration + tap button, free app on old OS floors. Use this page if you already own one. Buy Ring 2 if you want the current ECG titanium shop SKU.
Who it is for
- Owners who already have Slim and want the official guide numbers in one place.
- People documenting the 2.2 mm / 2 g / 5 m water class versus Ring 2’s 2.55 mm / 50 m guide.
- iOS 11+ or Android 6+ users still pairing a working Slim.
- Anyone who wants haptic alarms / timers from the Slim feature list.
Who should skip it
- Anyone shopping a new Circular. The live shop is Ring 2 only.
- Buyers who want 50 m / 100 m water or an ECG — Slim’s guide is 5 m / 30 min and no ECG row.
- People who need a 10–14 day OEM battery table.
- Anyone treating release-notes “Slim deprecated” as a promise of new firmware forever.
Key differentiators
- Official guide: 8.8 × 2.2 mm and 2 g — Circular’s thinnest published ring.
- IP68 to 5 m for 30 minutes (not salted water).
- Tap button + vibration motor; up to 20 days of memory.
- Free app; iOS 11.0+ / Android 6.0+ on the guide.
Caveats
- Not in the current shop collection. Do not write a US add-to-cart.
- Outer-shell alloy is not named on the fetched Slim spec block (accessed 2026-09-19). Guide care copy only says changeable outer-shells can scratch. Do not invent titanium or aluminium.
- Circular is not intended to diagnose, treat, cure, or prevent disease without a clinician (guide safety).
- Shop social-proof or third-party review numbers are not OEM specs — omit them.
Ring-category specs
Same rows on every ring page (Oura, Ultrahuman, RingConn, Galaxy Ring, Circular).
| Attribute | Value | Source / note |
|---|---|---|
| Materials | Inner: non-allergenic, nonmetallic clinical-grade biocompatible resin. Changeable outer-shell (care section). Outer alloy not named on the fetched spec block (accessed 2026-09-19). | Circular Slim user guide §16 / care |
| Width | 8.8 mm | Circular Slim user guide — Ring size & characteristics |
| Thickness | 2.2 mm | Circular Slim user guide |
| Weight | 2 grams | Circular Slim user guide |
| Sizes | 8 sizes, US 6–13 | Circular Slim user guide |
| Finishes | Not listed as named colorways on the fetched Slim spec block (accessed 2026-09-19) | Circular Slim user guide |
| Battery (OEM) | Up to 5 days; rechargeable 24–31 mAh Li-Ion, non-replaceable | Circular Slim user guide §16 |
| Charging (OEM) | Spec: 60 min. Charging chapter (2026-09-19 evening re-pull): 45–60 minutes from empty at 5.5 V; first-use calibration ≥45 minutes at 100%. | Circular Slim user guide §16 and charging chapterCite the section. Do not average with Ring 2’s shop 30-minute line. |
| Charging case (OEM) | Magnetic charger (high-end polymer in the spec). Not Ring 2’s 700 mAh Case 2. Shop no longer lists a Slim charger SKU on 2026-09-19. | Circular Slim user guide; shop.circular.xyz/collections/all |
| Water resistance | IP68: 5 m for a maximum of 30 minutes. Not recommended in salted water. Care section repeats the same 5 m / 30 min line. | Circular Slim user guide — Waterproof / care |
| Sensors | 3-LED oximeter (IR, red, green); 3-axis accelerometer; digital temperature. I/O: tap-activated button + vibration motor. | Circular Slim user guide §16 |
| Sleep tracking | Sleep analysis on the Circular app feature family (quality score, stages including deep and REM, on the shared Circular feature pattern). Quote the guide; Slim spec does not add ECG. | Circular Slim user guide features / app |
| Activity / fitness | Activity analysis / live HR / SpO2 on the Circular app. Tight-grip sports can impair PPG (guide accuracy notes on the Circular family). | Circular Slim user guide |
| App | Circular app (App Store and Google Play). Free app on the spec block. | Circular Slim user guide |
| Subscription / data access | Not published | Circular Slim user guide compatibility |
| Phone platforms | iOS 11.0 or later, or Android 6.0 or later | Circular Slim user guide — Compatibility |
| Wireless | Bluetooth Low Energy 4.2 to 5.0 | Circular Slim user guide |
| On-ring storage | Up to 20 days of data | Circular Slim user guide — Memory Capacity |
| US price (dated) | Not listed on shop.circular.xyz, 2026-09-19 | shop.circular.xyz/collections/all |
| Price band | Discontinued compact ring | Derived from missing shop listing + live user guide |
| Announced | Previous generation; Slim user guide still published 2026-09-19 | circular.xyz/user-guide-circular-slim |
| Availability | User guide live; shop collection is Ring 2 / Case 2 / accessories only (2026-09-19). Release notes: Slim deprecated. | shop.circular.xyz; circular.xyz/release-notes |
Circular Slim extras
Unique to this line or SKU. Other rings keep the first table aligned and swap this extras list.
| Attribute | Value | Source / note |
|---|---|---|
| Versus Circular Ring 2 | Slim: 8.8 × 2.2 mm, 2 g, sizes 6–13, 5 days, 5 m / 30 min, no ECG row. Ring 2: 7.8 × 2.55 mm, 3 g, sizes 6–14, shop 8 / guide 7 days, guide 50 m / 30 min, single-lead ECG. | Slim user guide; Ring 2 shop + user guide |
| Firmware status | Circular release notes label “Circular 1 Pro & Slim deprecated.” Do not promise ongoing feature parity with Ring 2. | circular.xyz/release-notes |
| Operating temperature | Usage −10–45 °C; charging 10–45 °C | Circular Slim user guide |
| FCC / IC | Slim guide regulatory block prints FCC ID 2A8NL-CIRCULAR110 and IC 29243-CIRCULAR110 — the same IDs as the 1 Pro guide. Cite the page; do not treat a shared ID as proof they are one radio SKU. | Circular Slim user guide — Regulatory (re-opened 2026-09-19 evening) |
Overview
Circular Slim is the discontinued compact Circular: 8.8 × 2.2 mm, 2 g, sizes 6–13, up to 5 days, IP68 5 m / 30 min, tap button + vibration. The shop is Ring 2 only.
Sensors, sleep, and activity
IR / red / green PPG, temperature, accelerometer, tap button, vibration. No ECG row on the Slim spec. Safety: not a diagnostic device.
Battery and charging
Up to 5 days; 24–31 mAh; spec 60 min / charging chapter 45–60 min at 5.5 V; up to 20 days of memory. Magnetic polymer charger — not Case 2.
App, subscription, and platforms
Circular app, iOS 11+ / Android 6+. Guide calls the app free. Do not invent Ring 2 coin-unlock language here.
Price
Not sold on the 2026-09-19 shop collection. Do not invent a used-market number.
Sources
- Circular — Slim user guide — accessed 2026-09-19
- Circular — user guide picker — accessed 2026-09-19
- Circular shop — all products — accessed 2026-09-19
- Circular — release notes — accessed 2026-09-19
Frequently asked questions
Can I buy Slim from Circular today?
Not on the shop collection we opened. The live hardware SKU is Circular Ring 2. Treat Slim as discontinued retail.
How deep can Slim go?
The official Slim guide: IP68, 5 meters for a maximum of 30 minutes, not recommended in salted water. That is not Ring 2’s 50 m guide line and not a 100 m Oura/RingConn claim.
Does Slim have ECG?
Not on the Slim spec block we opened. Single-lead ECG is the Ring 2 story. Do not copy it here.
What are the OS floors?
Slim guide: iOS 11.0 or later, or Android 6.0 or later. Ring 2’s fetched shop/guide pages did not restate those floors.
Official product page: Circular Slim. Specs: Circular Slim specs.