NIA WH260BT Bluetooth Headphones with FM Radio Playback Bluetooth V5.0 specification version, communication system, and 8–10 hours of battery backup Time needed to charge: 1 to 1:30 hours Communication maximum: 10M Complementary Bluetooth profiles: HFP, HSP Card, AVRCP, and A2DP Multiple decoding: WAV/WMA/MP3 Range of radio frequencies: 87.5-108 MHz; diameter of speaker: NdFeB 40 mm 32 ohm is the speaker impedance. Response to frequency: 20–20,000 Hz