1.Combine 40mm dynamic speakers , perfectly guarantees high fidelity sound. 2.Enhance the sound insulation, easy to isolate external noise 3.Scalable design, can suit difference head shape. 4.A 2.5 charge gives you up to 13 hours of continuous playback Chip CSR8635 Bluetooth Version V5.0 Battery 300mAh Product size L175*W75*h185mm Net weight 180g Wireless working range 10M (without obstacles ) Speaker Φ40mm Speaker sensitivity 103±3db at 1khz;1mw Profiles supported A2DP/AVRCP/HSP/HFP Impedance 32Ω±15% Speaker frequency 20Hz-20KHz Input voltage / current DC5V/1A Play time Up to 13H Talk time Up to 15H Charging time About 2.5H Standby time Up to 600H