Quick overview from the supplier:
Bluetooth Headphones Panasonic RB-M500BGE-C, Sand Beige, Over size, 30 Hours Playback
30 Hours Playback: On a full 4 hours charge, plus quick 15 minutes charge for 2 hours playback.
https://www.panasonic.com/mea/en/consumer/home-entertainment/headphones/overhead/rb-m500b.html
