I remember, about 100 years ago being enthralled by my Father showing me a 'magic wallet', so I think these were bought for the shop out of nostalgia as much as anything!
However, having said that they are a very good idea. Not taking up too much room and with spaces for 6 credit or debit cards, they measure just 10cms x 7.5cms. are black with contrasting grey and have RFID protection - not needed in Dads day, I'm not sure there were even Credit Cards then !!
RFID Blocking Protection
Many credit cards now have personal information embedded in them in the form of RFID (Radio Frequency Identification) tags.Unfortunately, identity thieves can now scan the tags and gain access to your important personal information. This Dents RFID wallet contains a protective shield that prevents your RF tags from being accessed.