5. Regarding the issue which the NFC function on the BTR1K might not sensitive sometimes

A: NFC belongs to the Near Field Communication technology. The NFC sensing areas on the BTR1K and smart phone must be close to each other to be sensed. The transmitted power of NFC on different brands mobile phones is also different (especially the one wearing the metal shell mobile phone will has the lower NFC sensing sensitivity). So, if the BTR1K can not pair with the phone wearing phone case  by NFC, it is recommended to remove the phone case and try again.