A purchase guide to Bluetooth oximeters and connected spirometers, with STAmina and Freediver Club compatibility evidence, dive-reflex limitations, seller reliability, and current pricing separated from marketing claims.
Move from devices to decisions: measure safely, test respiratory training, follow body-weight trends, read recovery cautiously, and fuel the work.
App logging and physiologically better measurement are different jobs. One device rarely does both.
Best low-risk Kraków purchase. STAmina and Freediver Club both list the model as supported. Local EU consumer protection and short delivery routes beat importing an unknown protocol.
Chosen for ear-vs-finger dive-reflex experiments. Turner Medical sent the complete bundle through Shipito and DHL Express. It was delivered in Kraków on 24 August at 15:39.
The only retail option found that is designed to record facial SpO₂ during a dive. It syncs to its own app after surfacing, without live phone streaming underwater.
Start with STAmina, then Freediver Club: both support external SpO₂ devices. Check the exact model against each app’s sensor list; Bluetooth alone does not establish compatibility.
Medisana PM 100 connect, PC-60FW, FS20F, Jumper JPD-500G/500F, Masimo MightySat and BM1000B.
Freediver Club supports external pulse oximeters on iOS and Android. It is the only freediving app with confirmed Creative SP-20 support in this comparison. Bluetooth sensors work in its mobile app, not its web app.
Good hardware may still expose a private protocol that your chosen training app cannot read.
STAmina lists EMAY EMO-90, Beurer PO60 and SilverCrest SPO55 as incompatible.
“Not named” means no reliable confirmation was found. It does not prove incompatibility. Companion apps can record data but do not automatically exchange live readings with a training app.
Element 08 is another freediving training app with live SpO₂ logging. Its documentation lists standard Bluetooth PLX, BerryMed, Viatom / Wellue and Masimo MightySat support. Family or protocol support does not confirm every model; Creative SP-20 is not explicitly named.
| Device | STAmina | Freediver Club | Element 08 | Freediving Apnea Trainer | Manufacturer / health app |
|---|---|---|---|---|---|
| Medisana PM 100 connect | Confirmed | Confirmed | Standard PLX supported; model not named | Not named | VitaDock+ confirmed |
| Wellue PC-60FW | Confirmed | PC-60F family named | Wellue family supported; model not named | Not named | ViHealth confirmed |
| Jumper JPD-500F | Confirmed | Confirmed | Not named | Confirmed | Model-specific app unclear |
| Berry BM1000B | Confirmed | Berry / BCI family named | BerryMed supported; model not named | Berry family named | Model-specific app unclear |
| Wellue FS20F | Confirmed | Confirmed | Wellue family supported; model not named | Not named | ViHealth confirmed |
| Masimo MightySat | Confirmed | Confirmed | Confirmed | Not named | Masimo Personal Health |
| Heart Sure A380 | Not named | Not named | Not named | Not named | Not established |
| JKS50C | Not named | Not named | Not named | Not named | Not established |
| Creative SP-20 | Not named | Confirmed | Not named | Not named | ViHealth confirmed |
| Nonin WristOx2 3150 BLE | Not named | Not named | Not named | Not named | NoninConnect + nVISION |
| OxiWear V3 | Not named | Not named | Not named | Not named | OxiWear Medical |
| OXAMA | Not named | Not named | Not named | Not named | OXAMA app |
Compatibility sources: STAmina supported sensors Freediver Club supported sensors Element 08 sensor FAQ Freediving Apnea Trainer history Freediving Trainer sensor page ViHealth VitaDock+ / PM 100 Apnio Aegean Breath
Core picks are ordered by job, not a false single ranking. Florian’s recommendation remains in its normal category and is visibly badged.
Strong budget hardware choice. STAmina says it personally tested the model. Freediver Club lists the PC-60F family; confirm the exact PC-60FW variant before relying on it. Finger perfusion remains the physiological limitation.
A practical app-first choice. STAmina and Freediver Club list it, Polish sellers stock it, and a local return is simpler than an overseas medical-device return.
Freediver Club supports live SpO₂ from the Creative SP-20. The complete Turner Medical bundle includes the recorder, adult ear probe and finger probe, avoiding the connector uncertainty of separately sourced European components. It travelled through Shipito and DHL Express and was delivered in Kraków on 24 August.
Purpose-built for underwater facial PPG, depth and motion. Records locally during the dive and transfers later. Bluetooth does not provide useful underwater phone streaming.
| Device | Why it is interesting | Compatibility | Price / source |
|---|---|---|---|
| Heart Sure A380 | Budget model, mainly Australian distribution. Confirm support with your chosen app. | App support unverified | A$54.15 |
| JKS50C | Budget option with inconsistent generic branding and sourcing. Confirm exact-model app support. | App support unverified | Verify exact model ID before buying |
| Wellue FS20F | Low-cost EU listing and personally tested by STAmina. | STAmina + Freediver Club + ViHealth | EU · about €37 Walmart US search · verify exact FS20F |
| Masimo MightySat | Premium fingertip signal processing and a named STAmina-tested device. | STAmina + Freediver Club + Masimo app | Typically US$250-350 |
| OxiWear V3 | FDA-cleared ear-worn continuous monitor with its own app. Not made for immersion. | OxiWear Medical | about US$500 |
| Nonin WristOx2 3150 BLE + 8000Q2 | Clinical-grade recorder supporting an ear clip, strong low-perfusion pedigree. | NoninConnect + nVISION | Roughly €1,000 with sensor |
Peripheral vasoconstriction can delay and degrade fingertip SpO₂ response. A finger may therefore display a reassuring value while a correctly designed ear sensor detects the arterial desaturation sooner.
An ear or facial sensor is the better candidate when your question is how fast oxygenation falls after vasoconstriction begins.
Finger units are cheap and convenient. Compare sessions under the same conditions, but do not interpret the value as central oxygenation during late apnea.
Consumer oximeters lag, lose signal under low perfusion and are not blackout predictors. Train with an attentive buddy. Do not hyperventilate.
Your intuition is right about the tissue: vasoconstriction reduces blood flow and oxygen delivery to the extremities. But a pulse oximeter does not measure oxygen stored in skin or muscle. It estimates haemoglobin saturation in the changing, pulsatile arterial component of the optical signal.
The dive reflex narrows vessels supplying the limbs. Finger tissue may become locally oxygen-deficient even while blood flow is prioritised toward the heart and brain.
SpO₂ is an estimate of arterial haemoglobin saturation. The algorithm isolates the pulse-related optical change and largely rejects static tissue and non-pulsatile blood.
Reduced flow lengthens circulation time to the finger and weakens the pulse waveform. Newly desaturated arterial blood is detected later, while the device may smooth, freeze, become noisy or lose the reading.
The ear is closer to the central circulation and often remains better perfused. It can reveal the falling arterial saturation earlier, but it must be a calibrated ear probe. An ordinary finger clip moved to the ear is not interchangeable.
In a 2007 apnea study, the finger nadir arrived about 15 seconds after the ear nadir. When the ear displayed 78%, the finger still displayed 94.6%. A 2026 study of 40 people performing maximal static breath holds found finger readings 9-15 percentage points higher when each hold ended and finger nadirs 18-23 seconds later. These are site-specific pulse-oximeter readings, not direct measurements of brain oxygenation.
A stable 50% with a credible pulse waveform is compatible with extreme arterial desaturation. But most pulse-oximeter accuracy is verified only from 70% to 100%, and cold, movement and dive-reflex vasoconstriction make a finger less trustworthy. The reading may be delayed, noisy or frozen.
The study reported an absolute difference of 9-15 percentage points, not a relative difference of 9-15%. It therefore does not mean 9-15% of a 50% reading, which would be 4.5-7.5 points. Pure arithmetic would turn finger 50% into ear 35-41%, but that is not a valid physiological prediction. The observed group difference was measured at the breath-hold breaking point, not established as a correction formula at 50%; the sites also reached their nadirs at different times, and readings below 70% lie outside the usual verified accuracy range.
For a freediver, the important implication is timing. If the finger finally reaches 50% after the breath hold, a more central site may have registered the fall earlier. Stop the session, breathe normally and do not chase a lower number. If saturation does not recover promptly, or there is confusion, blue colour, chest pain, seizure, loss of motor control or blackout, seek urgent medical help.
The earlobe is a better-perfused, faster site for estimating arterial haemoglobin saturation, so it is often a better proxy for the oxygen content of blood being delivered centrally. It does not measure blood inside the brain or the oxygen available to brain tissue.
Brain oxygenation also depends on haemoglobin concentration, cerebral blood flow, blood pressure, CO₂, metabolism and autoregulation. During apnea, rising CO₂ and the dive response can increase cerebral blood flow and partly preserve brain oxygen delivery even while arterial saturation falls. Measuring the brain requires a cerebral method such as forehead near-infrared spectroscopy, and even that is not a personal blackout predictor.
Evidence: 2026 maximal static breath-hold study 2007 apnea comparison FDA accuracy guidance cerebral NIRS in elite freedivers cerebral blood-flow response to apnea blood flow and finger response delay ear canal under vasoconstriction why a finger clip should not be moved to the ear underwater forehead prototype
Treat Wellue, Medisana, Creative, OxiWear and Nonin 3150 as dry-land devices. Nonin’s IP33 protects against limited spray, not submersion.
Records on the face during the dive. Its phone connection is for configuration and later transfer. Water absorbs 2.4 GHz Bluetooth too strongly for reliable phone streaming.
A dive watch may log wrist optical data, but wrist placement, sampling and closed ecosystems make it a poor substitute for a real-time apnea oximeter.
A portable spirometer can trend FVC or slow VC. It cannot measure residual volume or total lung capacity, so it cannot directly calculate all the air physically present in your lungs.
The Pro version claims Bluetooth FVC trends. Florian’s Geekbuying listing displays “Sold Out” when rendered for Germany, but that does not establish global availability, discontinuation or variant-specific stock. Basic/Pro descriptions are mixed and the app has poor legacy ratings. Buy only if the seller confirms Pro, pairing, destination stock and returns in writing.
Selected as the full-spirometry device after the MIR seller could not supply the ordered Spirobank Smart. The SP70B measures FVC, FEV1, ratio, PEF and curves. Its companion-app history remains weaker than MIR, but verified Medisave stock made it the route that actually produced a device.
Still the stronger supported ecosystem on paper, with 19 parameters including FVC, direct iOS or Android connection, personal trends and report export. In practice, Respira could not supply the ordered model and offered the FEV1/PEF-only Smart One instead. That substitute was rejected and the Contec SP70B became the selected device.
For coaching or clinical-style workflows where slow VC, inspiratory VC and full forced spirometry justify the cost. Overkill for a personal monthly capacity trend.
Do not compare absolute values across brands. Use technique notes, symptoms and calibration status alongside the graph.
Here, “confirmed” refers to the device maker’s own app or published SDK. It does not imply compatibility with STAmina, Freediver Club or any oximeter app.
| Device | Confirmed app / platform | Phone support | Software confidence |
|---|---|---|---|
| BreaThru Pro / Plus | BreaThru app; iOS can save maximum breath to Apple Health | iOS + Android | Confirmed, weak reviews |
| Contec SP70B | Contec Lung Doctor / regional companion software | Bluetooth claimed | Legacy risk Supply conflict and older iOS connection complaints |
| MIR Spirobank Smart | MIR Spirobank app plus documented third-party SDK | iOS + Android | Strong confirmation |
| MIR Spirobank II Smart | MIR Spiro app | iOS + Android | Strong confirmation |
| MIR Smart One | MIR Smart One app | iOS + Android | Confirmed Still lacks FVC |
App sources: MIR Spirobank Smart BreaThru iOS BreaThru Android Contec iOS app history OXAMA app
| Device | Verdict | Price |
|---|---|---|
| MIR Smart One | Good consumer app, but measures only FEV1 and PEF. Not the right tool for vital-capacity tracking. | EU · €119 Official US shop · US$139 |
| MIR Spirobank OXI | Adds fingertip oximetry to the Spirobank platform. Useful consolidation, but it is not an ear sensor and has no confirmed STAmina or Freediver Club support. | Official US shop - US$225 |
| AioCare Patient | Excellent full forced + slow spirometry concept, including VC/ERV/IRV, but Polish listing is sold out. | 1,399 PLN (~US$376) watchlist International quote channel |
| NuvoAir Air Next | Well-engineered full Bluetooth home spirometry ecosystem. High price and limited regional availability. | EU · about €560 NuvoAir international shop |
Delivery dates are estimates until a Kraków address is entered. Channel confidence reflects buyer protection, return distance, seller identity and whether the listing is current.
Short return route, named legal entity and EU consumer rights. Best for Medisana and MIR when stock is physically confirmed.
The cancelled SP70B order shows why a product page alone is not stock evidence. Seek written confirmation for discontinued or unusual devices.Platform protection up to 20,000 PLN (~US$5,263) and local fulfillment can outweigh a higher sticker price.
Check seller score, invoice, exact model and hygiene-return restriction before opening sealed probes.Strong US delivery and returns, but Poland eligibility, VAT and international return friction depend on checkout.
The PC-60FW offer was sold and shipped by Amazon.com when checked. Prefer Amazon EU if the same ASIN appears.Established cross-border channel with 14-day returns and many positive public reviews, but warranty logistics can be slower.
The BreaThru page displays “Sold Out” for the rendered Germany destination only. It does not establish global or variant-specific availability.A real large marketplace, but wrong region for Kraków and recent independent service scores are poor.
Useful as evidence that BreaThru still circulates, not as a recommended international buying route.Established UK medical supplier with company and MHRA wholesale details published. It shows 14 SP70B units and an enabled order button.
Confirm export delivery, VAT treatment and warranty support before ordering from Poland. A US forwarding address is irrelevant to this UK source.A Bluetooth logo and recycled product photo are not evidence of model identity, app protocol or calibration.
Ask for a settings-screen photo showing the exact model, return address and warranty issuer.Earlier rounded USD equivalents retain the rate recorded when each offer was checked. New 6 August conversions use NBP table 151/A/NBP/2026: 1 USD = 3.7236 PLN and 1 GBP = 5.0134 PLN. Values exclude card FX spread, VAT, duties, forwarding and shipping. NBP exchange-rate table
Channel evidence: Allegro buyer protection Medwil returns Geekbuying BreaThru listing Geekbuying returns Geekbuying independent reviews Takealot independent reviews
Consumer pulse oximeters provide estimates. Motion, temperature, pigmentation, nail coverings and low perfusion can alter results. This guide is not medical advice.
FDA pulse oximeter basicsNever train breath-holds in water alone. An oximeter does not prevent hypoxic loss of consciousness. Avoid hyperventilation and use trained supervision.
DAN freediving safetyKey prices and stock were rechecked 6 August 2026. Taxes, delivery, forwarding and exchange rates vary by destination. Reconfirm exact model and arrival date at checkout.
ATS/ERS spirometry standard