Quick answer
Aqara U200 is a documented mortise-cylinder retrofit candidate; Nuki Pro fits specified cylinder formats. Confirm the exact mechanism and emergency-key function before buying.
Research shortlist
These are conditional cylinder-retrofit candidates, not universal mortise-case replacements. Aqara U400 and other replacement deadbolts are excluded from this mortise shortlist.
| Product | Research use case | Sourced features | Decision limit |
|---|---|---|---|
| Aqara Smart Lock U200 | Cylinder format | Lock type: Retrofit actuator for mortise cylinder or deadbolt; Door compatibility: Euro-profile/select Scandi mortise cylinders with emergency function; single-cylinder US deadbolts; Installation: Retrofit; retains existing lock and keys | U200 documents Euro-profile/select Scandi mortise compatibility; Nuki documents Euro-profile/selected Swiss cylinders. |
| Nuki Smart Lock Pro (5th Gen) | Emergency function | Lock type: Interior cylinder actuator; Door compatibility: Euro-profile and selected Swiss round cylinders; no knob cylinder compatibility; Installation: Retrofit over existing interior key | Verify outside-key operation with an interior key inserted before fitting a retrofit actuator. |
What to check before buying
| Decision factor | What to establish |
|---|---|
| Cylinder format | U200 documents Euro-profile/select Scandi mortise compatibility; Nuki documents Euro-profile/selected Swiss cylinders. |
| Emergency function | Verify outside-key operation with an interior key inserted before fitting a retrofit actuator. |
| Handle operation | A rotating actuator is not evidence of lifting a multipoint handle; obtain exact mechanism approval. |
| Physical clearance | Match cylinder protrusion, mounting and manual entry to the manufacturer installation instructions. |
Aqara Smart Lock U200
Why it belongs here: For cylinder format, the US / Europe / global record documents Lock type: Retrofit actuator for mortise cylinder or deadbolt; Door compatibility: Euro-profile/select Scandi mortise cylinders with emergency function; single-cylinder US deadbolts; Installation: Retrofit; retains existing lock and keys; Physical key: Yes; existing original key.
Who should consider it: Buyers assessing cylinder format who can meet the documented Aqara Smart Lock U200 installation and operating requirements.
Before choosing: U200 documents Euro-profile/select Scandi mortise compatibility; Nuki documents Euro-profile/selected Swiss cylinders.
Evidence limit: Aqara Smart Lock U200 is assessed for cylinder format using manufacturer documentation; this does not establish a comparative security test result.
Full sourced specification recordNuki Smart Lock Pro (5th Gen)
Why it belongs here: For emergency function, the Europe record documents Lock type: Interior cylinder actuator; Door compatibility: Euro-profile and selected Swiss round cylinders; no knob cylinder compatibility; Installation: Retrofit over existing interior key; Physical key: Yes, when cylinder has emergency function.
Who should consider it: Buyers assessing emergency function who can meet the documented Nuki Smart Lock Pro (5th Gen) installation and operating requirements.
Before choosing: Verify outside-key operation with an interior key inserted before fitting a retrofit actuator.
Evidence limit: Nuki Smart Lock Pro (5th Gen) is assessed for emergency function using manufacturer documentation; this does not establish a comparative security test result.
Full sourced specification recordHow we chose
Selection centres on cylinder format, emergency function, handle operation, physical clearance. These are conditional cylinder-retrofit candidates, not universal mortise-case replacements. Aqara U400 and other replacement deadbolts are excluded from this mortise shortlist. This is source-based research, not a hands-on test or star-rated ranking.
Read the complete methodologyCommon questions
Can Aqara U400 replace any mortise lock?
No. Its documented format is a single-cylinder replacement deadbolt, not a universal mortise mechanism.
Is a compatible cylinder enough for a multipoint door?
Not necessarily. Handle-lift behaviour and the whole lock mechanism need approval, not just the cylinder profile.
Sources and verification
Official documentation consulted 5 October 2026. Specifications are manufacturer statements, not independent measurements. Check the exact regional model before buying.
- Aqara Smart Lock U200 — Official product or announcement
- Aqara Smart Lock U200 — Official supporting specifications/support
- Aqara Smart Lock U200 — Official supporting specifications/support
- Nuki Smart Lock Pro (5th Gen) — Official product or announcement
- Nuki Smart Lock Pro (5th Gen) — Official supporting specifications/support
- Nuki Smart Lock Pro (5th Gen) — Official supporting specifications/support
- Nuki Smart Lock Pro (5th Gen) — Official supporting specifications/support
- Nuki Smart Lock Pro (5th Gen) — Official supporting specifications/support
- Nuki Smart Lock Pro (5th Gen) — Official supporting specifications/support
- Aqara U200 lock format and emergency function
