This program produces the same buttons that Paypal's website produces. The difference is, you don't have to be online to make your buttons.

You can set the:

Item NameItem
Number
Price
Currency
Company Logo
Button Style
Successful Url
Rejected Url
Shipping address
Can the buyer buy more than one

All of this can be done offline with no need to go online. This means you can have your page ready to be uploaded when you connect instead of waiting to produce buttons the next time you can get on.