Key Benefits

• Improves training by monitoring real-time core temperature changes.

• Tracks heat strain to help manage performance and recovery.

• Guides safe heat training through personalised zone insights.

• Supports long-term adaptation with measurable progress scores.

• Lightweight, wearable sensor with app integration, and 6-day battery life.

The CORE 2 Thermal Sensor is the world’s most advanced wearable for real-time core body temperature monitoring—now redesigned to be 48% smaller and 30% lighter. Built for serious athletes, it helps you master thermoregulation so you can train smarter, adapt faster, and perform better.

Heat is a powerful training tool—done right, it can improve endurance, pacing, and recovery. CORE 2 makes this safe and measurable. With features like the Heat Strain Index and Heat Zones, it shows how hard your body is working to cool itself. The Heat Training Load and Heat Adaptation Score help track progress over time, guiding you towards adaptations that unlock performance gains.

Seamlessly integrating with Garmin, Wahoo, and other ANT+ or Bluetooth devices, CORE 2 connects your heat data to your existing training ecosystem. With a six-day rechargeable battery, it’s built to last through the toughest training weeks. Lightweight, non-invasive, and data-rich, CORE 2 is the definitive tool for mastering thermoregulation and pushing athletic potential further.

What’s In The Box?
-CORE 2 Thermal Sensor
-CORE 2 HRM Strap Clip
-Magnetic USB-C Charging Cable
-Product Information Guide
-Fully Recyclable Packaging

Technical Specifications
Compact Size: 41.9 x 29.4 x 7.1mm (no clip) | 45.1 x 32.6 x 9.6mm (with clip)
Weight: 8.6g (no clip) | 11.4g (with clip)
Battery: 6 days; up to 30 days with standby mode enabled
Power Supply: USB-C magnetic adapter cable (included)
Connectivity: Bluetooth low energy (BLE), ANT+ (2.4 GHz band)
Waterproof: up to 1.5m (IPX7 rating)
Research-backed accuracy: mean difference range of -0.01°C to +0.23°C

Core develops advanced wearables for accurate, continuous monitoring of core body temperature, with applications in sports, wellness, and health. Founded by Wulf Glatz and brought to life by Greenteg AG—a Swiss engineering company specialising in sensor technology—the brand was created to translate industrial-grade thermal insights into practical, wearable formats for health, sport, and workplace safety. Today, Core is trusted by athletes, performance specialists, and individuals who want to better understand their body’s response to heat—helping them train smarter, recover more effectively, and adapt with science-led precision.

With our Healf Curation Process, we do the work for you. Shop with confidence knowing that every item has been tried, tested, and curated for you.

Learn more about each step—Brand Discovery, Expert Validation, and Community Testing—here.

Install the mobile app:
Available on iOS and Android, the CORE App lets you track and review your heat data, manage the sensor’s settings, and complete firmware updates.

Pair CORE with your sports tech:
Pair the CORE sensor with your HR monitor, sports watch, bike computer, and training platforms for seamless integration.

Track your trends over time:
Review your heat data in the CORE app, track your heat acclimatization progress, and develop heat awareness to stay cool and perform your best on race day.

Integrate into your training software:
Integrate your heat data into training software like TrainingPeaks and Golden Cheetah so you and your coach get get a more informed picture of your performance.