I bought these for my child's studies, but I haven't used them because I purchased headphones instead. The case has gotten some dirt and scratches from storage. The contents are in good condition. In-ear headphones with remote control, featuring a frequency response of 20Hz - 20kHz and a sensitivity of 100dB/mW for high-quality sound. - Brand: maxell - Type: In-ear - Remote Control: Yes - Frequency Response: 20Hz - 20kHz - Impedance: 16Ω - Sensitivity: 100dB/mW Thank you for looking.