1, one-way retractable headphone for MP3 2, good quality and competitive price 3, ROHS and CE 4. 3.5mm plug 1, one-way retractable headphone for MP32, good quality and competitive price3, ROHS and CE 4. 3.5mm plug5, speaker size : 10φmm6, ImpedanceL 32Ω7, Sensitivity :115dB/mW8, Frequency Response: 20-20000HZ9, Cord length : 100cm iphone earphone