If the light on your cuffs is flashing red, this indicates that the battery is low. 

To charge your cuffs, simply use the charging cable and connect them to a power source.

You will be able to recognise whether The BFR Cuffs are charging via the light ring - a steady white light blinking on-off-on indicates that the cuff is charging. 

A quick note on power sources: The BFR Cuffs will charge when plugged into most devices, yet some higher-power sources (65+ watt laptop and mobile phone chargers) will not charge your cuffs.