Zemismart S1-K Smart Euro Cylinder Lock with Keypad, Card and App

The Zemismart S1-K turns the door you already have into a keyless smart door. It replaces the standard euro cylinder found in most uPVC, composite and timber doors with mortice locks. There's no drilling and no new lock: you swap the cylinder using a hex key. You can then unlock with a code, a card, your phone or the backup key, and see who came and went in the Tuya app.

Want fingerprint unlock on a timber door? See the A270-Z.

Need a surface-mounted lock with fingerprint on both sides? See the R5.

Four ways to unlock

• Code: enter your PIN on the backlit keypad.
• Card: tap one of the two key cards on the reader.
• App: tap to unlock in the Tuya or Smart Life app over Bluetooth.
• Key: two backup keys for emergencies.

Codes for guests, cleaners and holiday lets

Create codes in the app and share them by message:

• Periodic codes: work only at set times, such as weekday mornings for a cleaner.
• Time-limited codes: work between two dates, ideal for Airbnb guests.
• One-time codes: work once, for a delivery or a tradesperson.

These codes work even when the lock isn't connected to the internet. That makes it a practical choice for holiday lets and rental properties.

Manage everything from the Tuya app

Check the battery level, see the unlock record (who unlocked, how and when), and add or remove family members. Unlock with one tap when you're nearby. Add a Tuya Bluetooth gateway (not included), and you can unlock and manage the lock from anywhere.

Battery powered, with a USB-C backup

The lock runs on one CR123A battery (not included). If the battery runs flat, plug a power bank into the USB-C port under the cover to power the lock, or use the backup key.

Will it fit my door?

The S1-K fits a standard euro profile cylinder, the keyhole shape used on most UK uPVC and composite front and back doors. It doesn't fit oval cylinders, rim cylinders (Yale-type night latches) or round cylinders.

Choosing the right size

Euro cylinders are measured from the centre fixing screw to each end (A and B). Take out the fixing screw on the edge of the door, remove your old cylinder, and measure both sides. Then pick the closest size:

Extension pieces are included so the length can be fine-tuned. There must be at least 30mm between the door frame and the centre of the keyhole, so the smart head has room to turn.

Fitting

There's no need to change the lock or the door. Remove the fixing screw, slide out the old cylinder, slide in the S1-K and tighten the screw. A hex key is included.

Specifications

What's in the box

• Zemismart S1-K smart cylinder
• 2 × smart key cards
• 2 × backup keys
• 2 × key tags
• Hex key
• User manual

Not included: CR123A battery, Tuya Bluetooth gateway.

Frequently asked questions

Will it fit my uPVC door?

If your door has a euro cylinder (the keyhole shape in the size guide above), it almost certainly will. Measure A and B from the centre fixing screw and choose the closest size.

My cylinder isn't the same length both sides. Can I still use it?

The sizes listed are equal on both sides. Choose the size that fits the longer side, using the extension pieces, or contact us before ordering if your measurements are very uneven.

Do I need Wi-Fi?

No. Code, card, key and Bluetooth app unlocking all work without Wi-Fi. A Tuya Bluetooth gateway is only needed if you want to unlock or check the lock while you're away.

What happens if the battery runs out?

The app shows the battery level so you can replace it in time. If it runs flat, power the lock through the USB-C port with a power bank, or use the backup key.

Does it work with Alexa or Google Home?

It's controlled in the Tuya or Smart Life app. Voice control isn't advertised for this lock.

Is it suitable for holiday lets?

Yes. Periodic, time-limited and one-time codes make it easy to give guests and cleaners access without handing over keys.