Proel HFBT bleutooth headphones. Driver size 40 mm, Frequency range 18 - 21000 Hz, Sound pressure level Spl 103 dB, THD 0.10%, Jack plug 3.5 mm stereo, Bluetooth® profiles HSP, HFP, A2DP, AVRCP , Bluetooth® version V 4.0 + EDR , Frequency range