FLE wristband with heart rate monitor

nRF51822

Brand: Makibes
Model: ID107
Bluetooth version: V4.0 BLE
Waterproof rating: Life-level waterproof
Main chip: Nordic nRF51822
Pulse sensor: Silicon labs Si1142
G-sensor: kx022-1020

Possible free firmware for similar but newer device:

https://github.com/StarGate01/chrzwatch-firmware

root@rpi2:/home/pi# grep Wrist screenlog.0
CD:57:1B:79:77:B2 Wristband
CD:57:1B:79:77:B2 Wristband
CD:57:1B:79:77:B2 Wristband
CD:57:1B:79:77:B2 Wristband