The service extends Apple's official warranty on such devices:
All Apple iDevices (Except iPhone).
If your device requires repair, and the warranty has expired, this service will renew the warranty on your device and allow you to contact the Apple Authorized Service Center for warranty.
You can check the current status of the warranty on your device (before and after order completion) on the official Apple website: https://checkcoverage.apple.com/
1. Only devices from 2014 release are supported.
Devices from 2013 and older are not supported.
Devices after Activation lock are not supported.
2. The term for which the warranty will be extended depends on how long the warranty period for the device has expired.
Warranty may be extended for a period of 5-12 months.
For each device, the maximum possible warranty period will be set.
But you can only find out exactly what this period will be in your case only upon the completion of the order.
3. The warranty status at the time of order does not matter.
If the warranty has not yet expired, but is already running out, this service will extend it.