Not all Fitbit Versa 3/Sense watch bands are compatible with your newer Sense 3/ Versa 4, especially on third party watch bands and adapters.
- Sense/Versa3 adapters may not be compatible with Sense2/Versa4;
- Sense2/Versa3 adapters are compatible with all Sense/Sense2/Versa3/Versa4.
In the following adapter image, a rim exists on older Sense/Versa3 adapters, obstructed in inserting the watch property on the newer models, but removed on newer Sense2/Versa4 adapters. Some silicone watch bands may be able to be forced into a slot. Here is a compatibility list and our collection of Fitbit watch bands & Adapters:
Fitbit Versa
Compatibility: Fitbit Versa 2
Fitbit Versa 2
Compatibility: Fitbit Versa
Fitbit Versa 3
Compatibility: Fitbit Sense
Fitbit Sense
Compatibility: Fitbit Versa 3
Fitbit Versa 4
Compatibility: Fitbit Versa 3, Fitbit Sense, Fitbit Sense 2
Fitbit Sense 2
Compatibility: Fitbit Versa 4, Fitbit Versa 3, Fitbit Sense
Source: