Help to identify my Granfather IWC pocket watch

Hello
Could you help me identify this model of pocket watch from my Granfather
Some informations i can read on :
Fab n°852662
Movement n°828275
Diam 48mm Gold 18K
I would to known the name of model ,some technicals infos and his market value
Many thanks by advance
Best Regards
Stéphane

Hello
Some more information I'm a novice

Thanks