product specification: ​1.model:f9 wireless headphones 2.bluetooth specification:v5.0 3.bluetooth profile:a2dp,avrcp, hfp;hsp 4.frequency band range:2.402 ~ 2.480 5.working voltage:3.2v~4.2v 6charging voltage:5v-1a 7.battery capacity of the headset: 50mah 8.battery capacity of the storage box:350mah 9.transmission distance:>10m x9 dual dynamic bass sound bluetooth earphone hook/in-ear stable sport wireless headphone 250mah tf card mp3 waterproof headset