It's not just about blocking transactions, with ShopSafe you can set a dollar limit per merchant, you can also do monthly recurring transactions of a particular

It's not just about blocking transactions, with ShopSafe you can set a dollar limit per merchant, you can also do monthly recurring transactions of a particular amount, and stop them when you want, by closing the number. So you can actually pay for a while, then block them. You can set custom expiration dates, which is nice if you have a future transaction, but want to make sure they don't bill after that. Even better each merchant gets a different CC number, so you have a much lower chance of your number being stolen. I'll typically make a 1 year card with a high limit for each online merchant. If it's a one off, I'll make a 1 month card with a dollar limit of exactly the transaction amount.