You do not need to have an amazon account to use the extension. Simply load an amazon product page in any world region to view price comparisons. The default price currency option will match the first amazon locale loaded. When available, additional tax information will be displayed when logged into your amazon account.
The right side button is used to see the prices of the current page's product. Hovering over this button will display these prices. If the product is not in stock in another region it will display as unavailable. Products not sold in another region will be listed as not found with a strikethrough style for easy identification. You may view this comparison in different currencies by selecting a currency in the dropdown menu at the bottom of this popup. This will trigger a page refresh with a new price comparison in your selected currency. Clicking on the URL of a new locale will redirect you to that locale's product page. Note: to quickly redirect to the best region product page simply click on the right side button that lists the best region price. If you are already on the best priced region, the button will display 'Best Region'.