The Fitbit Charge HR was the first Fitbit model to use Heart Rate monitoring.
It was succeeded by the Fitbit Charge 2 in 2016.
The Fitbit Charge HR watch straps are changeable, however they do require the use of a tool and a screwdriver and are not as simple as the newer Fitbit Watch Straps to change.
If you're not sure what straps are compatible with your Fitbit, check out our extensive compatibility guide here.
There are a range of styles of Watch Straps for Fitbit:
Fitbit's official website can be viewed here