Colorful LED lights: seven-color transform cool breathing light, which will help you be more charming. Headphones have a variety of options for listening. With a built-in TF card slot, you can use the TF / Micro SD card with the loaded MP3 music and listen to the song directly on the headset. Designed with Bluetooth 5.0 CSR chipset for lower power consumption and higher compatibility. Compatible with all phones, tablets, laptops, any Bluetooth-enabled device or device with a 3.5mm audio jack. Built-in microphone: Supports hands-free calling and voice report caller ID. With the latest enhancements, your voice sounds clearer in a noisy environment. Specification Name: B39. Uses: wireless headphones, voice headsets. Bluetooth version: V5.0. Bluetooth mode support: A2DP 1.2, AVRCP 1.0, HSP, HSF 1.5. Frequency: 2.402-2.480GHZ, 2.4G ISM band. RF performance: receiver sensitivity: -84dBm; transmit power up to 4dBm. Frequency response: 20 Hz-20 KHz. Signal to noise ratio (SNR): 70Db. Total harmonic distortion rate (THD) 0.1%. Power indicator: Red and blue indicators flash alternately. Headphone charging: rechargeable 400MAH lithium battery. Charging port: mini 5-pin USB charging interface. Normal charging time: 2.5 hours. Talk time: up to 10 hours. Standby time: up to 20 days. Working temperature: -20 C -55 C. Other features: support status indicator, charging indicator display. Note: There might be a bit color distortions due to different computer resolutions. Please allow 1-3mm error due to manual measurement, make sure you do not mind before you bid. Package included: 1 x Bluetooth headset. 1 x charging cable. 1 x 3.5mm audio cable. 1 x Chinese and English user manual.