CST58 : Prepaid card SAAR (reply card) carried by "Cable car 'Rheinseilbahn Köln'"

CST58 : Prepaid Card SAAR (reply card) 12F "President Heuss" (Mi P47A ; Antwortteil)
Card carried by cable car on the Rhine “Rheinseilbahn Köln' 2.8.1958

Postmarked in Köln-Deutz "Deutscher Philateliststentag" dated August 2, 1958
(Temporary office installed near the cable car for the Philatelic Congress of Cologne in 1958) 
+ arrival cachet Merzig "Uber 100 Jahre Stadt" (Saar) dated August 5, 1958 on back
Rare

This document comes with a reprint of the vintage photo of cable car 'Rheinseilbahn Köln' Cologne.