Greelan Technology is one of the leading China 3.5mm jack headset manufacturers and suppliers, and also a professional factory and company, welcome to wholesale and buy cheap and high quality school education 3.5mm jack headphone products for English learning and check the price with us. Language Laboratory 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 Lab Headphone Detail: Language Laboratory Headphone Packing : 1). Packing Measurement MODEL ITEM QTY(PCS) G.W.(KGS) N.W.(KGS) MEA(CM) GD109 3.5mm 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: