Most chest-strap heart rate monitors still work the way they did a decade ago: a coin-cell pod, no controls and an app that can be fiddly to pair. Fourth Frontier's Frontier X2 tries to fix that. It adds a small screen, a physical button, haptic alerts and a rechargeable battery, and it streams a continuous ECG to your phone. TechRadar's reviewer found it accurate enough to prefer over the long-standing Polar H10 benchmark, but the price is the big question.
Frontier X2 at a glance
Characteristics and opinion
The X2 is a chest-worn sensor pod that clips onto a strap. Unlike most rivals, you can check that it is connected and start a workout from the device itself using its button and display, so you are not left guessing whether recording has begun. Charging is over micro-USB rather than swapping coin batteries, and Fourth Frontier quotes around two weeks of typical use per charge.
Where the X2 stands out is feedback during training. It buzzes when you move between heart rate zones, which makes it easier to stay in the right intensity without looking at a watch. Alongside heart rate it reports Strain, Stress, HRV and Breathing Rate, similar to what Whoop users will recognise, and it can livestream an ECG trace to the app or share it with a clinician. In testing, its averages landed within about 2 bpm of premium GPS watches.
Key specifications
- Dimensions: 73mm x 24mm x 13mm
- Weight: 25g without strap
- Connectivity: Bluetooth
- Water resistance: IP67
- Battery: about 14 days of typical use, micro-USB charging
- ✓Screen and button for easier interaction
- ✓Haptic feedback for real-time monitoring
- ✓Advanced metrics for detailed analysis
- ·High initial cost and subscription fees
- ·Not designed for use in salt water
How to choose
Choose the Frontier X2 if you want ECG-grade insight, on-device controls and real-time zone alerts, and you are happy to pay a premium. Some extras, including a Readiness score, VO2 Max and sleep stages, sit behind an optional yearly subscription, so factor that into the total cost. If you just need accurate heart rate data for a watch or bike computer, the Polar H10 costs a fraction of the price and also supports ANT+, which the X2 lacks.
Conclusion
The Frontier X2 is one of the easiest and most informative chest straps to live with, thanks to its screen, button, haptics and rechargeable battery. Its high price and subscription paywall mean it is best suited to athletes and health-focused users who will actually use the ECG and recovery metrics; everyone else will get better value elsewhere.
