Smartwatches that fit under your mechanical watch

Smartwatches that fit under your mechanical watch

Smartlet is a modular strap that lets you wear your smartwatch with your mechanical watch, on standard lug widths from 18mm to 24mm (23mm coming soon). The smartwatch sits underneath the wrist, against the skin. No modification, fully reversible.
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Compatibility

Smartwatches that fit under your mechanical watch

Smartlet is a modular strap that lets you wear your smartwatch with your mechanical watch, on standard lug widths from 18mm to 24mm (23mm coming soon). The smartwatch sits underneath the wrist, against the skin. No modification, fully reversible.
14+
Brands with full guides
100+
Models compatible
18-24mm
Supported lug range
0
Modifications required

Choose your smartwatch

Apple
Apple Watch
Series 0 to 12 - SE - Ultra 1 to 4
ECG, SpO2, heart rate, skin temperature, crash detection
20mm / 22mmView guide →
Samsung
Galaxy Watch
Watch 4 to 9 - Classic - FE - Ultra
ECG, BIA body composition, SpO2, heart rate
20mm / 22mmView guide →
Garmin
Forerunner
FR 55 - 165 - 255 - 265 - 570
Pulse Ox, heart rate, HRV, training readiness
20mm / 22mmView guide →
Polar
Polar
Vantage - Grit X - Ignite - Pacer - Unite
10-LED heart rate, HRV, SpO2, orthostatic test
22mmView guide →
Google
Pixel Watch
Pixel Watch 1 to 5 (41mm & 45mm)
ECG, SpO2, heart rate, skin temperature, Fitbit
20mm / 22mm (with dedicated adapter)View guide →
Huawei
Watch GT
GT 2 to GT 7 - GT Runner
ECG, SpO2, TruSeen heart rate, skin temperature
20mm / 22mmView guide →
Fitbit
Fitbit
Charge 5 - 6 - Versa - Sense
ECG, EDA stress, SpO2, sleep staging
20mm (with dedicated adapter)View guide →
Fitbit
Fitbit Air
Screenless tracker - coming soon
Optical HR, SpO2, skin temperature, AFib, HRV
Proprietary (adapter included)View guide →
Whoop
Whoop 5.0 / MG
Whoop 5.0 - Whoop MG
HRV, heart rate, SpO2, respiratory rate, skin temp
20mm (with dedicated adapter)View guide →
Garmin
Venu
Venu - Venu 2 - 3 - 4
SpO2, heart rate, HRV, body battery, sleep
18mm / 20mm / 22mmView guide →
Withings
ScanWatch
ScanWatch - 2 - Light - Nova
ECG, AFib detection, SpO2, breathing disturbances
18mm / 20mmView guide →
Coros
Coros
Apex - Pace - Nomad
Heart rate, SpO2, HRV, EvoLab, multi-band GPS
20mm / 22mmView guide →
Suunto
Suunto
Race - Vertical - 9 Peak - Run
Heart rate, SpO2, HRV, barometric altimeter
20mm / 22mm / 24mmView guide →
Panther
Panther Eclipse
Eclipse
18mmView guide →
Amazfit
Amazfit
GTR - GTS - Balance - T-Rex - Bip
Heart rate, SpO2, GPS, barometer
20mm / 22mmView guide →
Casio
G-Shock
G-SQUAD - G-LIDE (connected)
Heart rate, step counter, GPS on some models
Third-party 22mm band adapterView guide →

All compatible smartwatches

Garmin Instinct
Instinct 2, Instinct 2X Solar, Instinct Crossover
22mm
Garmin Epix
Epix Gen 2, Epix Pro 42 / 47 / 51mm
20mm / 22mm
Fossil
Gen 6, Gen 6 Wellness, Hybrid HR
18mm / 20mm / 22mm
Mobvoi TicWatch
Pro 5 GPS, Pro 3 Ultra, E3
22mm
Xiaomi
Watch S3, Watch 2 Pro, Watch Color 2
22mm
OnePlus Watch
Watch 2, Watch 2R
22mm
Polar Grit
Grit X2 Pro, Grit X
22mm
Polar Ignite
Ignite 3, Ignite 2
20mm
Polar Pacer
Pacer, Pacer Pro
20mm / 22mm
Huawei Band
Band 8, Band 9
18mm
Honor Watch
Watch 4 Pro, Watch GS 3
20mm / 22mm
Oppo Watch
Watch 4 Pro, Watch X, X2, X3, X3 Mini
18mm / 20mm / 22mm
Realme Watch
Watch 3 Pro, Watch S Pro
22mm
TAG Heuer Connected
Calibre E4 45mm, Golf Edition
22mm
Montblanc Summit
Summit 3, Summit Lite
22mm
Tissot T-Touch
T-Touch Connect Solar
21mm
Kospet Tank
Tank T3 Ultra, Tank Pro 2
24mm
Casio G-Shock
GBD-200, DW-H5600, GBX-100
22mm (third-party adapter)
Oura Ring
Ring 4, Ring 3
N/A - ring form factor
Panther
Eclipse, Solstice
18mm / 20mm

26mm variants: not compatible

51mm (26mm lug): not compatible

26mm variant: not compatible

Proprietary band on most models, third-party adapter required

Not wrist-based, not compatible with Smartlet

Explore further

Browse all
Watch Brands
27 brands covered→
Browse all
Iconic Models
50+ iconic models→

Choose your Smartlet

Step by step

Replace your strap
01

Replace your strap

The watch adapters seat in your mechanical watch's lug holes in place of the spring bars. Classic, Shadow or Titanium. The spring bar tool is in the box.

Connect your wearable
02

Connect your wearable

Your smartwatch attaches to the central part of the bracelet with its own adapter (Apple Watch, Whoop, Fitbit, Galaxy or Pixel Watch) or a pair of standard watch adapters. Zero modification to the mechanical watch.

Wear both simultaneously
03

Wear both simultaneously

Both watches sit on the same wrist. The smartwatch sits underneath, against the skin.

Questions

Frequently asked questions

  • What lug widths does Smartlet support?
    Smartlet takes smartwatches with standard lugs from 18mm to 24mm, with the standard smartwatch adapters in the box. Some smartwatches use a proprietary band attachment and a dedicated adapter, such as the Apple Watch, the Galaxy Watch 8 series and Ultra models, the Pixel Watch and the Fitbit Charge 5 and 6. Select your smartwatch above to see which adapter it uses.
  • Do smartwatch sensors still work when attached to Smartlet?
    The sensors face the skin underneath the wrist, and the bracelet is sized by its links so the smartwatch sits snug. For a reading with medical weight, put the smartwatch back on its own band and follow the manufacturer's instructions. Notifications and the other functions work as usual.
  • Does Smartlet work with all mechanical watches?
    Smartlet works with mechanical, automatic and quartz watches with standard spring bars and a lug width between 18mm and 24mm (23mm coming soon). This covers most men's and unisex watches, including Rolex, Omega, Tudor, TAG Heuer, Breitling, IWC, Seiko and hundreds of other brands.
  • Is Smartlet reversible?
    Yes. The watch adapters seat in the lug holes in place of the spring bars, using the spring bar tool in the box, and your watch can go back on its original strap at any time. Nothing on the case or lugs is modified.