INCH and INCH duo version 5.3
...
https://etrelchargingsolutions.atlassian.net/wiki/spaces/Home/pages/2836398134/Firmware+4.0.#5.0
CAUTION: if the charging station uses a mobile connection, please check how much data you have leased in the package. Upgrade system file size is aprox 78 80 MB. If you have less data available in the package, we recommend a local upgrade otherwise additional costs may be incurred by your mobile provider!
...