This calculator unlocks your radio/navigation system with an ERC code. Note that it doesn't work with the newest models, here's the list of models it works with:

Supported models: NDDN-W57, NDDN-W58, ND3T-W57, NHBA-W62G, NHDT-W57, NHDT-W58, NHDT-W58G, NHDT-W59, NHDT-W59G, NHDT-W60G, NHZN-W57, NHZN- W58, NHZN-W59C, NHZN-W59G, NHZN-W61, NHZN-W61G, NHZN-W60G, NSCN-W59C, NSCN-W60, NSDN-W59, NSDN-W60, NSCP-W61, NSZA-W61G, NSZT-W60, NSZT-W61G, NSZT-W62G, NSCT-W61, NSDT-W59, NSDD-W61, NH3T-W57, NHZT-W58G, NHZT-W58, NH3N-W58, NHZD-W62G, NHDA-W57G, NHDA-W61G, NSCP- W62, NSCP-W64, NSZT-W64