Greelan Technology is one of the leading China usb headset manufacturers and suppliers, and also a professional factory and company, welcome to wholesale and buy cheap and high quality school education usb headphone products for English learning and check the price with us. USB Port Language Laboratory Headphone Language Lab Headphone Features: 1)Headphones: a)  Frequency Response: 125Hz ~ 8000 Hz, ± 17 dB (0dB = 20uPa The) (input power = 1mW); b)  Electrical Impedance: 32Ù ± 20%; c)  The characteristics of sound pressure level (sensitivity): the ≥ 100dB/1mW (0dB = 20uPa). 2)Microphone: a) Frequency response :40-20000HZ b) Type: electrets microphone; c) Receiving voltage response: -47 ± 2 dB (0 dB = 1V/Pa); d) Directional type: two-way. Language Laboratory Headphone Detail   Language Laboratory Headphone Packing  1). Packing Measurement MODEL ITEM QTY(PCS) G.W.(KGS) N.W.(KGS) MEA(CM) GD609 USB Headphone 40 9.00  7.80  56*48*35 2). Packing Details   Payment & Delivery 1)Payment Terms: TT, L/C at sight. 2)Delivery Time: 10-15 days after getting the deposit Real Language Lab Headphone Case