Answer:
They are Visa cards that you buy from a shop and top-up with money before using. It is a bit like a gift card or a travel card. You top it up whenever the value on it is too low for you. Some of the benefits of this are:
•Perfect for sharing money with family abroad
•A great gift idea
•A Travel Cash Card for your Holiday
•A great budgeting tool
•"Posh" pocket money
•Secure and Private Online Shopping
•No Credit checks needed to buy one
•No bank account needed
http://www.cngbs.com/products-services/merchant-services.asp