Kaadas K20 Pro Max vs Interlock Mercury X6: Battle of Smart Locks

The Kaadas K20 Pro Max is the better pick if you want an established brand and a heavy push-pull handle. The Interlock Mercury X6 is the better pick if you want palm vein recognition, the Tuya Smart app ecosystem and a slimmer lock on a wooden door. Both have 3D facial recognition, fingerprint, a 4-inch indoor screen and a mechanical key backup.

We install both brands, so this comparison comes from fitting them on HDB and condo doors, not from a spec sheet. We also say who should not buy the Mercury X6, because it does not suit every door.

Quick verdict

• Choose the Kaadas K20 Pro Max if: you trust the Kaadas name, like a substantial push-pull handle, and do not need smart home automation.
• Choose the Mercury X6 if: you want palm vein as well as face and fingerprint, use Tuya Smart or Smart Life, and your door is wood within 40 to 60mm thick.
• Choose neither yet if: your door is metal or glass, or you are not sure of the thickness. Send us photos first and we will tell you what fits.

Which Kaadas model is this comparison about?

This page benchmarks the Kaadas K20 Pro Max. Kaadas also sells newer models such as the K70SE, which has a 4.94-inch indoor display and 3D facial recognition. This page compares the K20 Pro Max only. For other Kaadas models and other brands, see our guide to Kaadas digital lock alternatives.

Feature comparison

Feature	Kaadas K20 Pro Max	Interlock Mercury X6
Biometrics	3D face, fingerprint (Sweden FPC sensor)	3D face, palm vein, fingerprint
Indoor screen	4.0-inch IPS	4-inch HD IPS
Intercom	Video and 2-way audio	Doorbell with 2-way audio and app alerts
App	Kaadas app (its own ecosystem)	Tuya Smart / Smart Life (open)
Gate pairing	Syncs with Kaadas R9KFV gate lock	Syncs with Mercury G3 gate lock
Body	Push-pull handle	Slim 19mm aluminium alloy body, Class C anti-pry cylinder
Door needed	Varies by door, confirm before buying	Wooden door, 40 to 60mm thick, 3 to 8mm door gap. Not for metal gates or glass doors
Price	Usually above $1,200	$849 now, usual price $899
Warranty	Varies by seller	1 year onsite, product and battery
Backup	Emergency power and mechanical key	USB-C emergency power and mechanical key

Prices change, so confirm the current price on the product page or on WhatsApp before you decide.

Face, fingerprint and palm vein

Both locks use 3D facial recognition, which does not accept a photo or video of your face. Both also have fingerprint readers. The Kaadas uses a Sweden FPC sensor, a well-known sensor brand.

The Mercury X6 adds palm vein recognition. It reads the vein pattern under the skin without touching the sensor, which helps people whose fingerprints have worn down and anyone with wet or dirty hands at the door. If you do not need that, the extra method will not change your daily use much.

App and smart home

The Kaadas app is built to manage the lock: users, logs and settings. It is simple and does the job if you only want to control the door.

The Mercury X6 runs on Tuya Smart, so if you already use Smart Life devices you can have it work alongside them. Be realistic about it: most owners use the lock for access and logs, and only a few set up automations around the door.

Door and gate setup in Singapore homes

This is where most buyers get caught. A digital lock has to fit your door, and in most HDB flats it also has to work with the gate in front of it.

• Kaadas: the K20 Pro Max pairs with the Kaadas R9KFV gate lock so one face scan can open both.
• Mercury: the X6 pairs with the Mercury G3 gate lock through our Advanced Dual Synchronised Module, so the gate and door unlock together. If you want both locks in one purchase, see the Mercury door and gate lock bundle.
• Mercury X6 clearances: at least 130mm from the door's internal handlebar and at least 80mm between door and gate. If your gate sits very close to the door, tell us before you order.

Who should choose the Kaadas K20 Pro Max

• You want a well-known brand with a long track record in Singapore.
• You prefer a heavy push-pull handle.
• You plan to pair it with the R9KFV gate lock.
• Your door is not suited to the slim X6 body, for example a metal door.

Who should choose the Interlock Mercury X6

• You want palm vein recognition on top of face and fingerprint.
• You use Tuya Smart or Smart Life.
• You have a wooden door within 40 to 60mm and want a slim lock.
• You want the lower price: $849 now against a Kaadas that usually costs above $1,200.
• You want installation included: we install it free, and a free fit check before purchase with a No-Fit, No-Fee guarantee.

Who should not buy the Mercury X6

Skip it if your door is metal or glass, if the door is thicker or thinner than 40 to 60mm, or if you want a longer warranty: the Mercury X6 has 1 year, which is shorter than some brands. Also note it is a doorbell with two-way audio, so visitors cannot see inside your home through it.

Final verdict

The Kaadas K20 Pro Max is a solid, familiar premium lock. The Mercury X6 gives you palm vein, the Tuya app and a lower price, as long as your door suits it. If your door is wood and the measurements fit, the X6 is the better value. If it does not fit, we will say so and point you to a lock that does.