Since this appears to be navigation or firmware data (CS11/TOM), ensure your device is compatible before attempting an installation.
Where did you this from? (e.g., a car manufacturer site, a GPS forum?) Datei herunterladen CS11TOMDE.7z.003
If you only downloaded .003 , you need to go back and download all preceding and succeeding numbered parts. Since this appears to be navigation or firmware
You cannot open this file by itself. It is one piece of a larger puzzle. a car manufacturer site
I can provide the specific steps for your hardware once I know the model!