Fourth Frontier makes four chest-strap heart rate monitors that record a true ECG, not just beat timing. Three are general wellness products for athletes, and one is an FDA-cleared medical device. This page compares them, and the Polar H10, on the specifications that decide which one fits.
Jump to: Which one | Range comparison | ECG access | Wellness versus medical | Frontier Premium | Model pages
Which Frontier fits
- You want a long battery and a screen-free strap: the Frontier Zone lasts around 30 days of typical use and costs GBP 179 with code 5KRUNNER (RRP GBP 199). It is sold on the UK and Europe store.
- You want a screen on the pod, and ECG streaming without a subscription: the Frontier X2 has a colour display and includes ECG streaming and export. It is GBP 405 or USD 405 with code THE5KRUNNER, from an RRP of GBP 579 or USD 579.
- You are in the US and want the longest battery: the Frontier X3 lasts around 4 months of typical use. It does not let you see or export the ECG trace.
- You have, or are being investigated for, a heart condition: the Frontier X Plus is FDA-cleared, reports rhythm status and needs a prescription. It is US only.
Range comparison
| Frontier X2 | Frontier Zone | Frontier X3 | Frontier X Plus | |
|---|---|---|---|---|
| Price | GBP |
GBP |
USD |
USD |
| Where sold | US, and UK and Europe | UK and Europe only | US only | US only, prescription |
| Classification | Wellness | Wellness | Wellness | Medical device (FDA 510(k)) |
| Screen on pod | Colour display | None | None | Colour display |
| Battery, typical use | Around 14 days | Around 30 days | Around 4 months | Around 14 days |
| Battery, continuous recording | Up to 24 hours | 7 days | 7 days | Up to 24 hours |
| Charging | Micro USB | USB-C | USB-C | Micro USB |
| Water rating | IP67 | IP67 | IP67 | IP22 |
| Bluetooth | 5.0 | 6.0 | 6.0 | 5.0 |
| Simultaneous connections | 3 | 3 | 3 | 1 (app only) |
| Vibration alerts | Yes | Yes | Yes | No |
| Training load, Body Shock | Yes | Yes | Yes | No |
| Rhythm status (AFib, bradycardia, tachycardia) | No | No | No | Yes |
ECG access: what you can see and export
An ECG strap records the heart’s electrical signal tens of times a second. Most sports straps pass on beat timing only, which is enough for heart rate and HRV but not enough to draw a trace. The Polar H10 is the only other mainstream strap that gives an athlete a waveform.
| Strap | ECG sampled / stored | What you can see and export |
|---|---|---|
| Frontier X2 | 250Hz / 125Hz | Live stream, PDF and data export, no subscription |
| Frontier Zone | 125Hz / 125Hz | Live stream and export with Frontier Premium only |
| Frontier X3 | 125Hz / 125Hz | Nothing. The trace is not displayed, streamed or exported |
| Frontier X Plus | 500Hz / 125Hz | Live stream, PDF and raw data download, included |
| Polar H10 | 130Hz, 14-bit | Streams over Bluetooth through Polar’s free SDK. A phone app must record it, and the strap cannot store ECG itself |
The Polar H10 is hardware only. You need separate ECG software, and it has none of the in-exercise features the Frontier straps add, such as vibration alerts and strain. It is competitive on one point: it can record an ECG.
Wellness versus medical
Fourth Frontier is a wellness company that also makes one FDA-cleared medical device. The X2, Zone and X3 are general wellness products. They are not medical devices and are not intended to diagnose, treat, cure or prevent any condition. The X Plus holds FDA 510(k) clearance for ambulatory ECG monitoring and is prescription only, for adults aged 22 and over.
That split explains the X3. Fourth Frontier says the X3 samples ECG inside the strap to calculate its metrics, but removed the ECG display to maintain a clear boundary between medical and non-medical products. Full ECG capability is reserved for the X Plus.
Frontier Premium
Frontier Premium is an optional subscription. On the X2, Zone and X3 it unlocks VO2 max, ventilatory thresholds, a readiness score, sleep staging and Garmin Connect. On the Zone it also unlocks ECG streaming and export. On the X3 it does not unlock ECG streaming. The X Plus does not use Premium. It has its own optional Weekly Cardiac Rhythm Report.
Store prices at 7 October 2026: GBP 14 a month on the UK store, and USD 15 a month on the US store.
Model pages
- Frontier X3 specifications
- Frontier X2 specifications
- Frontier Zone specifications
- Frontier X Plus specifications
Reviews and further reading
- the5krunner Frontier Zone review
- the5krunner Frontier X2 review
- the5krunner Frontier X Plus review
- Heart rate monitoring hub
- All watch and sensor specifications
Fourth Frontier X2
24x7 ECG, real-time alerts and sports tracking.
Fourth Frontier X3
Screen-free heart rate strap with USB-C charging, US only.
