Smartlet One
Smartlet One
One concept. Three different personalities
Wear your Fitbit Charge with your mechanical watch | Smartlet
Key facts
Fitbit Charge Charge 5, Charge 6
18 to 24mm lug widths
All sensors fully operational
Zero case modification
No tools required
Fully reversible
Fitbit Charge compatibility
Wear your Fitbit Charge and your mechanical watch at the same time
Yes. Smartlet is compatible with the Fitbit Charge 5 and Charge 6. The Fitbit Charge uses a proprietary band attachment - Smartlet supports it via its universal module. All health sensors remain fully operational. No modification to the mechanical watch required. Fully reversible in seconds.
Fitbit Charge 5 and 6 pack exceptional health density into a slim tracker. ECG, EDA stress sensor, SpO2, continuous heart rate. Smartlet replaces your mechanical watch strap via the standard spring-bar system and positions your Fitbit Charge on the same wrist. A dedicated adapter is included in the Smartlet box.
The problem
Choosing between health data and horological heritage every morning.
The solution
Smartlet replaces your mechanical watch strap and positions your Fitbit Charge on the same wrist. Wear both simultaneously, without compromise.
Step by step
How it works
01
Replace your strap
Smartlet replaces your mechanical watch strap via the standard spring-bar system. Classic, Shadow, or Titanium. No tools required.
02
Connect your Fitbit Charge
Fitbit Charge requires the dedicated Smartlet adapter, included in the box. Smartlet replaces your mechanical watch strap via the standard spring-bar system. The Fitbit Charge connector snaps onto the Smartlet module. No modification to the mechanical watch.
03
Wear both simultaneously
Both watches sit on the same wrist. All Fitbit Charge sensors maintain direct skin contact and operate normally.
All Fitbit Charge sensors remain fully operational. All Fitbit Charge health sensors remain operational with Smartlet. ECG, EDA stress sensor, SpO2, and continuous heart rate maintain direct wrist contact for accurate readings.
Compatibility
Fitbit Charge models supported
| Model | Smartlet compatible | Lug width | Release year | Case size |
|---|---|---|---|---|
| Charge 5 | Compatible | Proprietary (adapter incl.) | 2021 | N/A |
| Charge 6 | Compatible | Proprietary (adapter incl.) | 2023 | N/A |
Charge 5
Proprietary (adapter incl.) · N/A
Charge 6
Proprietary (adapter incl.) · N/A
Frequently paired
Mechanical watches worn with Fitbit Charge
Rolex
Submariner · Datejust · GMT · Daytona
19mm / 20mm / 21mm
Omega
Seamaster · Speedmaster · De Ville
18mm / 19mm / 20mm / 21mm
Tudor
Black Bay · Pelagos · BB58 · Royal
18mm / 19mm / 20mm / 22mm
TAG Heuer
Carrera · Aquaracer · Monaco · F1
19mm / 20mm / 22mm
Seiko
SKX · Presage · Prospex · 5 Sports
18mm / 20mm / 22mm
Breitling
Navitimer · Superocean · Chronomat
20mm / 22mm / 24mm
IWC
Portugieser · Pilot · Portofino · Aquatimer
18mm / 20mm / 21mm / 22mm
View all brands
Complete guide
Also compatible
Other smartwatches
Apple Watch
Series 0 to Ultra 3
20mm
Samsung Galaxy Watch
Series 4 to 7
20mm
Garmin Forerunner
255 to 965
22mm
Garmin Venu
Venu 2 / 3 / Sq 2
20mm
Polar Vantage
V2 / V3 / M2
22mm
Google Pixel Watch
1 / 2 / 3
Proprietary
Huawei Watch GT
GT 3 / GT 4 / GT 5
22mm
Withings ScanWatch
Light / 2 / Nova
20mm
Coros
Apex / Pace / Vertix
22mm
Suunto
9 / Race / Vertical
22mm
Whoop
Whoop 5.0 / MG
Proprietary
View all
Smartwatch compatibility guide
Questions
Frequently asked questions
Can I wear a Fitbit Charge and a mechanical watch at the same time?
Yes. Smartlet makes it possible to wear your Fitbit Charge and a mechanical watch simultaneously on the same wrist. Smartlet replaces your mechanical watch strap via the standard spring-bar system and holds your Fitbit Charge against the same wrist. Both watches run at the same time. All Fitbit Charge health sensors maintain full skin contact and operate normally. You no longer have to choose between your health data and your mechanical watch every morning.
Which Fitbit Charge models are compatible with Smartlet?
All Charge 5, Charge 6 models are compatible with Smartlet. The Fitbit Charge uses a proprietary connector. A dedicated adapter, included in every Smartlet box, bridges it to the Smartlet module. The setup takes under two minutes and requires no tools. Smartlet is compatible with any mechanical watch between 18mm and 24mm lug width, covering the vast majority of the market including Rolex, Omega, Tudor, TAG Heuer, Seiko, Breitling, and IWC.
Will Fitbit Charge sensors still work when used with Smartlet?
Yes, all sensors remain fully operational. Smartlet positions the Fitbit Charge against your wrist with full skin contact maintained at all times. The following sensors continue to function normally: ECG, EDA stress sensor, SpO2, continuous heart rate, sleep score. There is no interference with the sensor array, and health data accuracy is unaffected.
Does Smartlet damage or modify my mechanical watch?
No. Smartlet replaces your standard watch strap using the existing spring-bar system. It makes no permanent modification to the watch case, lugs, or dial. The process is fully reversible in seconds. Your mechanical watch is unaffected and can be worn independently at any time by reinstalling its original strap.
