1. First, make sure that you have registered your KOSS headphones. If you haven't, you can do so by following the steps below:

• Return the registration cards that came with the headsets
•  Complete KOSS's online registration form. www.koss.com (Please Note - Completing this form will only register one headset. To register more than one headset you must fill out this form once for each headset you wish to register)
• Call the registration number, 1-888-877-5677. (One call per headset)

2. Once your headsets are registered you should securely package up the headsets that need repaired/replaced with a check or money order for $10.00 per headset to cover shipping costs. Send the headsets with your check or money order to: 

KOSS Lifetime Limited Warranty
4129 N. Port Washington Avenue
Milwaukee, WI 53212