This product is either discontinued or we cannot get that from suppliers.
Garmin Soft Strap With Electrodes 010-11254-02, 2.4 GHz ANT Wireless, Bluetooth 5.0, Range 3.0 meters, Compatability ANT+, Bluetooth.
This strap is meant to replace the back portion of a separately available Garmin heart rate monitor it does not contain the heart rate monitor module itself. The strap is equipped with skin electrodes.