The thing that trips people up when buying a smart lock is not the features — it is the door itself. Fingerprint, 3D face and palm-vein unlocking all sound good, but door thickness, whether it is a fire door, whether there is a security gate in front of it and which way it swings are what actually narrow the choice.
So this guide starts with the door, and gets to the features afterwards.
1. Measure your door first
Take these measurements before ordering — none of them can be worked around later:
- Door thickness. Hong Kong residential timber doors are commonly 35–50mm; older tenement and commercial solid doors can be thicker. Every lock states a supported range.
- Swing direction. Standing outside: does the door open left or right, inward or outward? This sets handle and latch orientation (adjustable on most models, but it has to be done at installation).
- Existing mortise body. Record the latch and lock-body type. Backset is the distance from the door edge or lock faceplate to the relevant lock centreline; it is different from the handle-to-cylinder centre distance. Have the installer identify and measure both against the selected manufacturer's dimension diagram.
- Frame and gap. Is there room in the frame for the strike plate, and how much play is there when the door is closed?
2. Hong Kong door types: what fits, what needs care
| Door type | Situation | Watch out for |
|---|---|---|
| Timber door | Confirm solid or hollow construction | Have the installer check thickness, condition and the chosen lock's approved door and fastening requirements. Do not assume reinforcement makes a hollow-core door suitable. |
| Timber door with security gate | The standard pairing in most flats here | The smart lock goes on the timber door; the gate keeps its own key. In daily use you still open two locks |
| Fire door | Escape routes and some flat entrances | The Buildings Department requires that a fire door complies with the construction requirements specified in its test or assessment report — including dimensions, ironmongery and intumescent strips — and that it is firmly fixed to the surrounding wall with no visible gaps. Drilling or modifying one may take it outside the tested specification, so check with building management and a professional before any work starts. |
| Glass or aluminium-framed doors | Offices and shopfronts | Most residential models will not fit; these need commercial bodies or glass-door-specific locks |
| Sliding doors | Small flats, mezzanines | Confirm door movement, latch and lock body against the manufacturer's approved applications; a push-pull handle name does not establish fit. |
3. Unlocking methods and who they suit
- Fingerprint. It can be convenient for daily use, but wet fingers, cuts and children's smaller fingerprints may affect recognition. Check the chosen model's supported users and backup methods.
- PIN. If supported, it can be a backup access method. Check temporary-code and padding-digit features by model, and manage authorised users carefully; padding digits do not guarantee protection from observation.
- 3D face. Hands-free, which matters when you arrive carrying shopping. Look for 3D — with depth information — rather than plain 2D image matching.
- Palm vein. Reads the vein pattern under the palm; may offer another method if fingerprints are difficult to read; compare the exact model's supported methods and conditions.
- App/Bluetooth. Bluetooth normally serves nearby access. Internet remote unlocking and remote logs require the exact model's supported Wi-Fi or gateway, account and service conditions; do not infer them from Bluetooth alone.
- Emergency access. Check the exact lock's documented backup route. If it has a physical key, keep an authorised spare accessible outside the flat; do not assume every smart lock has a keyway. Any required emergency cable or power source must also be accessible when you are locked out.
4. Models to compare
- EZVIZ DL05 lever fingerprint lock (IP65) — entry level, fingerprint plus PIN, check the complete model's permitted location, exposure and installation instructions; IP65 alone does not establish outdoor suitability.
- EZVIZ DL20FVS Plus — lever handle with 3D face and palm vein, for timber doors where you want to keep a conventional handle look.
- EZVIZ DL50FVS Plus — push-pull panel with 3D face and palm vein.
- EZVIZ DL50FVX — dual camera, 3D face and palm vein; the most fully featured of the four.
If you would rather not change the lock at all but still want to see who is outside, the EZVIZ EP4 4K smart door viewer replaces the existing peephole and leaves the mortise alone. Full range in smart door locks.
5. Flat battery, power cut, failed read — then what?
- Batteries. Smart locks run on internal or replaceable cells and warn you on the lock and in the app when they run low. Do not wait for empty.
- Emergency power. Confirm the model's emergency-power connector, approved power source and procedure. Keep the compatible cable and power source accessible outside the locked flat. Supplying power does not itself bypass authentication.
- Mechanical key. Store the emergency key somewhere other than inside the flat: office, car, or with someone you trust.
- Building power cuts. If the model uses its own charged batteries, local access may continue during a building outage. Networked features can still be unavailable; confirm the documented emergency-access route.
6. Can I fit one in a rented flat?
It may be possible if a qualified installer confirms the door and chosen lock are compatible and any fire-door requirements and approvals are met. Obtain the landlord's written consent and agree reinstatement before work starts; drilled holes or a replaced mortise may need restoration at the end of the lease. Keep the original lock and keys, and have the reinstatement assessed and carried out appropriately. Check building-management rules as well.
7. Questions to ask your installer
Have a qualified installer assess the door and lock before drilling or replacing the mortise. Fire-door modifications require professional confirmation of the tested or assessed construction and applicable approvals; they are excluded from self-installation advice. Ask:
- Will this model fit my door — thickness, type, security gate and all?
- Are new holes needed, or can the existing cut-out be reused?
- If it has to be reinstated later, is that possible, and at what cost?
- Where does responsibility sit — the lock carries brand warranty, but who covers the installation work?
For installation arrangements and pricing, WhatsApp +852 9847 9793 with a description of your door and we will come back to you.
8. Locks and cameras together
EZVIZ locks share an app with the brand's security cameras, but a door-opening notification with a camera view requires confirmed model, gateway and app support, and you can extend it with door/window sensors and motion sensors (Zigbee models need the A3 gateway). For which camera ecosystem suits you, see Reolink vs EZVIZ vs SpotCam; to start from scratch, read our home CCTV guide.
FAQ
Can a photo fool 3D face recognition?
3D recognition reads facial depth rather than matching a flat image. Check whether the product page says 3D or 2D — "face recognition" alone does not tell you which.
What is palm vein recognition?
It reads the vein pattern beneath the palm and works without contact. If fingerprints are difficult to read, it can be another method to compare. Recognition performance and supported users remain model-specific.
How long do the batteries last?
It depends on how often the door opens, how much face recognition is used and how often the lock talks to Wi-Fi. Real-world figures vary widely, so rather than trusting a headline number, enable the low-battery alert and change them when it appears.
Can I give a temporary code to a helper or relative?
Check whether the complete model supports time-limited or use-limited codes, how they expire, and whether a gateway or internet connection is needed. Give access only to authorised users and remove it when no longer required.
Several family members, including elderly parents — how should I set it up?
Choose supported methods that each person can use reliably and register authorised users separately where the model allows. Manage backup codes securely; do not assume one shared PIN is the best setup for every household.
Ordering and warranty
EZVIZ locks are Hong Kong licensed stock with brand warranty. Confirm current stock, delivery timing and collection arrangements before ordering; our Kwun Tong location is for stock and collection. Not sure whether your door will take one? WhatsApp +852 9847 9793 with a photo of the door and the existing lock body.
