Speakers and receivers for mobile phone, note book, digital camera, mp3, mp4, ipod, etc. Parameters for reference: Impedance 8+/-15% Inputpower(Max.) 0.5W(0.7W) Resonance Frequency 1250Hz+/-15% S.P.L 90+/-3dB/0.5W/ at (1.0K,1.2K,1.5K,2.0KHz) Distortion <10%