So that we could get the largest number of customers using Android Pay we have integrated with Visa Token Services (VTS). This allows us to offer Android Pay to both Flexi Debit and Visa Credit Card customers.
Using tokenization technology ensures that a customer's 16-digit card number isn’t stored on the mobile device. Instead a replacement 16 digit number is masked in a token on the phone. Each token can only be used once.
This ensures an extremely high level of security and protects against fraud, however as we are using VTS and not the MasterCard equivalent we can only provision Visa products.
Hope this makes sense.