What this solves
When the auditor is at the dock and the laptop is in the office.
Operator-driven workflows need the record where the work happens — at the cabinet, at the truck, at the bench. The S20 generates a tamper-resistant PDF on the device, exports over USB, and shows the operator the recent record history right on the screen. No portal trip, no IT ticket, no waiting.
3 + 1
external probe channels plus external door magnetic sensor support. One device covers a multi-zone cabinet or three monitored locations.
On-device PDF
recording PDFs generated on the device at end-of-record. USB-exported to a computer — no laptop required at the cabinet.
Flight Mode
cellular silenced for depots, tarmac, in-flight. PT100 cryogenic logging continues — uploads when device exits Flight Mode.
Why teams choose S20
Built to do real work at the device.
Three external probe channels + door magnetic
Three bottom channels for temp, humidity, NTC, or PT100 — plus optional external door magnetic sensor. One device covers a multi-zone cabinet or three monitored locations.
On-device PDF + USB export
Start Recording from the menu. When you Stop, the device generates the PDF locally. Plug into a laptop over USB and the file is yours — no cloud round-trip required.
Flight Mode for depots and air cargo
Long-press power, switch to Flight Mode. Cellular silenced for in-warehouse, on-tarmac, or in-flight conditions. Logging continues; data uploads when the device exits Flight Mode.
Recent history on-screen — for the inspector at the cabinet
Short-press menu shows recent record data directly on the device. Pair with the sound + light alarm and cloud push for full chain-of-custody — no laptop needed at audit time.
Why ZKSCool
Why ZKSCool S20 — when the record happens at the device.
| 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-S20 |
|---|---|
| Display | 2-inch LCD |
| On-device controls | 2 buttons — Power, Menu |
| On-device menu functions | Start Recording · Alarm Query · One-key WiFi · Exit · Flight Mode · Restart · Shutdown · history view |
| On-device PDF + USB export | ✓ Generated on Stop Recording · USB export to computer |
| Bluetooth printer pairing | — |
| On-device alarm log | Last 10 alarms viewable |
| Storage capacity | 60,000 readings |
| Internal sensor | Built-in temperature + humidity |
| External probe options | Temp + humidity · NTC · PT100 · external door magnetic sensor (门磁线) |
| External probe channels | 3 channels + charging port (bottom) |
| Additional built-in event sensors | — |
| NTC operating range | −40°C to +80°C |
| PT100 cryogenic operating range | −200°C to +150°C |
| 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 |
| WiFi | 2.4G IEEE 802.11 b/g/n |
| Bluetooth | — |
| Location | LBS · uploaded with each reading |
| SIM | External SIM card slot · rubber-plug sealed |
| Cloud platform | zTMS · REST API · webhooks |
| Cloud alarms | Cloud platform push: over-temp, low-battery, power-loss |
| Offline buffer | 60,000 readings local · auto-upload on reconnect |
| Battery | Polymer lithium 4,000 mAh |
| Operating duration | Up to 15 days (4G mode) |
| Standby current | ≤200 µA |
| Charging | USB · DC 5V / 1A |
| Low-battery behavior | Red LED blinks every 5s when <20% · cloud platform low-battery push |
| IP rating | IP65 — manufacturer manual; test certificate pending engineering |
| Mounting | Rear magnet · magnetic installation |
| Storage temperature | −40°C to +65°C |
| Working temperature | −10°C to +55°C |
| CE marking (EU) | ✓ Certified (2026-04-30) |
| FCC certification (US) | ✓ Certified (2026-05-27) |
| RoHS (EU) | ✓ Certified (2026-02-14) |
| China 3C / CCC | — Not in current registry |
| Explosion-proof certification | — |
| 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 S20 is deployed
Operator workflows — storage, transport, audit.
Multi-zone warehouse
Three cabinets, one device
Three external probe channels cover three adjacent cabinets — or three zones in one walk-in. Add a door magnetic sensor for chain-of-custody on the most sensitive cabinet.
Depot & air cargo
Flight Mode for depots and tarmac
Switch into Flight Mode at the loading depot or before air-cargo handover. Cellular silenced; PT100 cryogenic logging continues. Data uploads automatically when the device exits Flight Mode at destination.
On-site audit
PDF + history at the cabinet
When the inspector arrives: short-press menu shows recent records on the screen. Stop Recording generates the PDF on the device. USB into a laptop — file delivered, no portal trip.
Validation service
One-stop validation service from the manufacturer.
ZKSCool offers a one-stop validation service. Whether your S20 deployment runs on GSP protocols [confirmed] or GxP / IQ / OQ / PQ [scoped per environment], our team configures the qualification package — so your QA team starts qualified.
✓ 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 S20 has 3 external probe channels (vs S20K’s 2), supports the external door magnetic sensor, generates PDFs on-device with USB export, has Flight Mode, and shows recent record history on the screen. The S20K is streamlined for continuous cloud-streaming and has the explosion-proof certification. Pick S20 when operators need to do real work at the device; pick S20K for set-and-forget cloud monitoring in standard or hazardous environments.
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 S20 logs every reading to internal memory throughout any signal outage and auto-uploads queued data the moment connectivity returns. 60,000-reading local buffer.
Yes. The S20 generates a tamper-resistant PDF on the device at end-of-recording and exports via USB. Records are timestamped and compatible with regulated electronic-record standards. Our one-stop validation service scopes the qualification package — GSP [confirmed] or GxP / IQ / OQ / PQ [per environment] — to match your deployment.
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 put the S20 in your operators’ hands?
Reply within 1 business day · Sample units available · Validation scope on request