Sleep Wearable Form Factor
Compare smart rings, fitness bands, and smartwatches for overnight sleep tracking: comfort, battery habits, and sleep metric depth.
Fitbit FB521GLBM-US 1.3 ounces Advanced Health and Fitness Smartwatch
Available offers (3)
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Current
1.3 ounces
Retailer
€177.94
Available to order
Price history by offer
Volatility: MediumFeatures
- All-day stress detection with cEDA
- ECG app for atrial fibrillation assessment
- Personalized Sleep Profile
- Built-in GPS and workout intensity map
- 40+ exercise modes and automatic exercise tracking
- 6+ day battery life
General specs
- Brand: Fitbit
- Model: FB521GLBM-US
- Seller: Retailer
- ID: B0B4MV1TGL
- batteries: 1 Lithium Ion batteries required. (included)
- manufacturer: Fitbit Inc
- Country of Origin: China
- Product Dimensions: 1.57 x 0.47 x 1.57 inches; 1.3 ounces
- Date First Available: September 23, 2022
- First listed by seller: May 29, 2025
If you are interested in more details, you can find full information on the seller's page.
Price History for seller Retailer
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Delivery to 
United States
United States
Available
Ever feel like your life's a whirlwind of stress and sleepless nights? The Fitbit Sense 2 might just be your new best friend. It's not just a smartwatch; it's like having a personal health coach strapped to your wrist. With all-day stress detection (thanks to cEDA), a daily Stress Management Score that tells you how chill (or not) you are, and an ECG app to keep tabs on your heart's rhythm, it's got your back. Oh, and it'll nudge you if your heart's doing the cha-cha when it shouldn't be, plus keep an eye on your SpO2 and other health stats.
Sleep like a baby with features that sound like they're from a luxury spa: a Sleep Profile that's all about you, detailed sleep stages, a Sleep Score to brag about, and a smart wake alarm that won't jolt you awake like your old alarm clock. And for those days when you're more couch potato than gym rat, it's got built-in GPS, a workout intensity map (because getting lost is so last year), and a Daily Readiness Score to tell you whether you're ready to conquer the world or just Netflix. With over 40 ways to track your sweat sessions and a design that laughs in the face of water (up to 50 meters, that is), it's ready for anything.
Wear it all day, every day, and never miss a beat—or a call, text, or notification, thanks to Bluetooth connectivity. Customize it to your heart's content with clock faces that match your mood, pay with a flick of your wrist using Fitbit Pay, and ask Alexa for the weather (or to tell you a joke). The battery? It lasts over 6 days, because who has time to charge every night? Plus, snag a 6-month Premium membership for deep dives into your health data. Because knowledge is power, right?
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| Brand | Fitbit | FITVII | Apple | Apple | Fitbit | Apple |
| Model | FB521GLBM-US | HM57 | MR8W3LW/A | MWXF3LW/A | 6514035 | MR9C3LW/A |
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| Price | €177.94 | €44.49 | €296.49 | €433.74 | €168.18 | €295.89 |
| Seller | Retailer | Retailer | Retailer | Retailer | Retailer | Retailer |
| Update | May 13, 2026 | Jun 24, 2026 | Mar 21, 2026 | Mar 21, 2026 | Jun 24, 2026 | Mar 29, 2026 |
| batteries | 1 Lithium Ion batteries required. (included) | 1 Lithium Ion batteries required. (included) | 1 Lithium Ion batteries required. (included) | 1 Lithium Ion batteries required. (included) | ||
| manufacturer | Fitbit Inc | FITVII | Apple | Apple | Apple | |
| Country of Origin | China | China | China | Vietnam | ||
| Product Dimensions | 1.57 x 0.47 x 1.57 inches; 1.3 ounces | 9.53 x 3.07 x 1.3 inches | 24 x 7.7 x 3 inches | 9.53 x 3.07 x 1.3 inches | ||
| Date First Available | September 23, 2022 | April 22, 2024 | February 1, 2024 | September 9, 2024 | February 1, 2024 | |
| department | mens | mens | mens | |||
| Item Weight | 1.34 ounces | 4.8 ounces | 8.1 ounces | |||
Fitbit FB521GLBM-US All-day stress detection with cEDA
€177.94
When this device makes sense
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