Reading their footer, it says: "The Privacy Visa Card is issued by Customers Bank pursuant to a license from Visa U.S.A. Inc." So, it seems they have some kind

Reading their footer, it says: "The Privacy Visa Card is issued by Customers Bank pursuant to a license from Visa U.S.A. Inc." So, it seems they have some kind of partnership with a bank, which is able to generate unlimited card numbers for them.