What this solves
Continuous cloud-streaming for fixed cold storage — including hazardous-area sites.
Continuous monitoring, real-time WiFi or 4G upload, tamper-resistant records for audit defense. Magnetic back, 2-button menu, one-touch WiFi — installed in under five minutes. Explosion-proof certification makes it deployable in regulated and hazardous-area environments.
2 + 1
external probe channels (one deep-cryogenic capable) plus one-touch WiFi configuration. Set-and-forget continuous streaming.
Ex-proof
explosion-proof certification (per 防爆合格证). Deployable in hazardous-area pharma, chemical, and regulated storage environments.
< 5 min
install time per refrigerator. Magnetic back, no tools, no drilling, no IT involvement. Move it later — nothing left behind.
Why teams choose S20K
Built for the everyday — not the exceptional.
Magnetic install in minutes
Magnetic back sticks to any metal refrigerator or cabinet. No tools, no drilling, no IT involvement. Move it later — nothing left behind.
One-touch WiFi config
Power on, press menu, connect. No app, no specialist setup. WiFi for fixed sites; 4G SIM for unreliable network.
Detachable probes
Two pluggable probe channels — one supports deep cryogenic. Swap for recalibration without removing the device or losing reading history.
Audit-ready out of the box
Tamper-resistant PDF export via USB. Local sound + light alarm on over-temp, power loss, low battery. Compatible with electronic-records standards.
Why ZKSCool
Why ZKSCool S20K — plug-and-play for cold storage, including hazardous-area sites.
| OTHER SUPPLIERS | ZKS-S20 | ZKS-S20K | |
| External probe channels | ~ 1 internal sensor (typical) · external probe usually 1 channel | ✓ 3 channels + door magnetic sensor support | ✓ 2 detachable channels — one supports deep cryogenic |
| PT100 cryogenic (−200°C to +150°C) | ~ Separate cryogenic SKU · premium tier | ✓ Same SKU — pluggable probe option | ✓ Same SKU — deep cryogenic probe option |
| On-device records | — Cloud-only · portal trip required | ✓ On-device PDF · USB export · history view + Flight Mode for depots and aircraft | ~ Cloud-based · on-device alarm log |
| Field deployment | ~ Drilling, brackets, IT involvement | ✓ Rear magnetic mount · pluggable probes · external SIM | ✓ Rear magnetic mount · one-touch WiFi · < 5 min install |
| Hazardous-area certification | — Rarely available | — — | ✓ Explosion-proof certified |
| Validation service | ~ Vendor-locked cloud · premium kits | One-stop · GSP global · GxP/IQ-OQ-PQ in selected countries | ✓ One-stop · GSP global · GxP/IQ-OQ-PQ in selected countries |
How it works
From box to cloud in under five minutes.
1
Stick on.
Magnetic back panel attaches to any metal refrigerator, freezer, or cold-storage cabinet. No drilling. No mounting bracket. No IT involvement.
2
Power on.
Long-press the power button. Green status light confirms boot. Plug in the detachable temperature probe through the side port if extended sensing is needed.
3
Connect.
Long-press menu, select one-touch WiFi, and confirm. Or insert a 4G SIM for sites without reliable network. The device begins uploading immediately.
4
Monitor.
zTMS Cloud receives readings in real time. Configure threshold alerts to email, SMS, or your existing systems. Export tamper-resistant PDFs via USB on audit day.
Specifications
| Model | ZKS-S20K |
|---|---|
| Display | 2-inch TFT color screen |
| On-device controls | 2 buttons — Power, Menu |
| On-device menu functions | Alarm Query · One-key WiFi · Exit · Restart · Shutdown |
| On-device PDF + USB export | — |
| Bluetooth printer pairing | — |
| On-device alarm log | Last 10 alarms viewable |
| Storage capacity | 60,000 readings |
| Internal sensor | Built-in temperature + humidity (open-port design) |
| External probe options | Temp + humidity · NTC · PT100 (one channel supports deep cryogenic) |
| External probe channels | 2 channels + charging port (bottom) |
| Additional built-in event sensors | — |
| NTC operating range | −40°C to +80°C |
| PT100 cryogenic operating range | Deep cryogenic (range engineering to confirm) |
| Temperature accuracy | ±0.5°C (0 to +65°C) · ±1°C (−40 to 0°C) |
| Humidity accuracy | ±5% |
| Local alarm | Sound + light · over-temp, power loss, low battery |
| Cellular | 4G — LTE-FDD, LTE-TDD, GSM (model variant) |
| WiFi | One-touch WiFi config (model variant) |
| Bluetooth | — |
| Location | LBS · uploaded with each reading |
| SIM | Standard SIM slot · rubber-plug sealed |
| Cloud platform | zTMS · REST API · webhooks |
| Cloud alarms | Cloud platform push: over-temp, low-battery, power-loss |
| Offline buffer | Local memory holds readings through signal loss · auto-upload on reconnect |
| Battery | Polymer lithium 4,000 mAh (S20 family — engineering to confirm) |
| Operating duration | Up to 15 days (S20 family — engineering to confirm for S20K) |
| Standby current | ≤200 µA (S20 family — engineering to confirm for S20K) |
| Charging | USB or dedicated power plug · DC 5V / 1A |
| Low-battery behavior | Red LED blinks every 5s when <20% · cloud platform low-battery push |
| IP rating | Engineering to confirm IP rating |
| Mounting | Rear magnet · magnetic installation |
| Storage temperature | −40°C to +65°C |
| Working temperature | −10°C to +55°C |
| CE marking (EU) | — Engineering roadmap |
| FCC certification (US) | — Engineering roadmap |
| RoHS (EU) | — Engineering roadmap |
| China 3C / CCC | — Not in current registry |
| Explosion-proof certification | ✓ Certified (2026-04-29 → 2031-04-28) |
| GSP compliance | ✓ Meets national pharmaceutical GSP requirements |
| 21 CFR Part 11 / EU Annex 11 design alignment | ✓ Designed around electronic-records principles |
| ISO 17025 traceable calibration | Available via our validation service |
| IQ / OQ / PQ validation | One-stop service — available in selected countries · scoped per customer environment · confirm coverage with our team |
Where the S20K is deployed
Fixed cold storage — wherever it lives.
Pharmacy & hospital
Pharmacy refrigerator monitoring
2°C–8°C continuous monitoring across pharmacy fridges. One S20K per door. Magnetic install — no cabinet modification.
Clinical lab
Lab freezer & reagent storage
Deep cryogenic probe channel covers −80°C ULT freezers for samples, reagents, blood, cell lines. Pluggable probes — recalibrate without downtime.
CDC & vaccine site
Vaccine cabinet monitoring
Validation service
One-stop validation service from the manufacturer.
✓ GSP [confirmed] · GxP / IQ-OQ-PQ [TBC — scoped on request]
✓ Calibration certificate (traceable)
✓ Standard Operating Procedure templates
✓ Pre-deployment qualification support
✓ Recalibration program (swap detachable probes)
Pairs with
The full cold-chain stack — one accountable team.
Frequently asked
Questions buyers ask us.
Both share the same body, magnetic mount, sensors, 4G + WiFi + LBS, and alarm system. The S20K is the streamlined cloud-streaming variant with 2 external probe channels, a simpler menu, orange-highlight selection UI, and the explosion-proof certification. The S20 adds a 3rd external channel, external door magnetic sensor support, on-device PDF + USB export, Flight Mode, and on-device history view. Pick S20K for set-and-forget cloud monitoring; pick S20 when operators need to do real work at the device.
WiFi for sites with stable corporate or facility network — hospitals, central pharmacies, lab buildings. 4G for clinics, distributed vaccination sites, and any environment where IT can’t provision WiFi access. Both versions upload to the same zTMS cloud — your dashboards and reports look identical regardless of which connectivity you chose.
Under five minutes per refrigerator. The magnetic back panel attaches directly to any metal cabinet — no drilling, no bracket, no IT involvement. Power on, long-press menu, confirm one-touch WiFi. The device begins uploading immediately.
The S20K logs every reading to internal memory throughout any signal outage and auto-uploads queued data the moment connectivity returns. No reading is lost.
Yes. The S20K generates tamper-resistant PDF exports via USB with timestamped records, and is compatible with electronic records standards used in regulated industries. Our one-stop validation service () scopes the qualification package — GSP [confirmed] · GxP [TBC] · IQ/OQ/PQ [TBC] — to match your environment.
The external probes are detachable / pluggable. When recalibration is due, swap the probe at the connector — no need to remove the device, no historical data lost, no downtime on the fridge being monitored. Our recalibration program handles the swap cycle.
Ready to evaluate the S20K?
Reply within 1 business day · Sample units available · Validation scope on request