Your grandfather was probably born on 6 August 1906, as one of the twins – see the parish records (in book of Čistá Nr.20). Moissel family lived in this city sure for a long time; see the land with the name of the family on the old cadastral map from 1840. Images are attached.
If you want to find more in parish records for town Lauterbach (today non-existent town Čistá, district Sokolov) they are on-line at Brno archive http://actapublica.eu (you must search under Státní oblastní archiv v Plzni).

But unfortunately I know nothing about linking Zettel Family ...see also http://boards.ancestry.com/thread.aspx?mv=flat&m=3322&am... last reply by schoenner...