Welch Allyn offer an online service to Register any Extended Warranty or Preventive Program purchased with a serial number. For devices without a serial number, registration is not required. However, please retain the registration card to provide the reference number when calling for service. Service will not be provided without the Reference Number related to your purchase. The reference number can be found in the bottom left corner of the back side of the card. Please follow the link to access the registration form through Welch Allyn. Extended Warranty and Preventive Program Registration