Power converter?

if I buy something electrical from the US and plug it in over here obviously itll fry. So I know I need some sort of power converting device but does anyone know where to get these from or their actual name?

http://cgi.ebay.co.uk/UK-240v-to-US-110v-Voltage-Converter-FREE-POSTAGE_W0QQitemZ5859181716QQcategoryZ14968QQrdZ1QQcmdZViewItem

Thats the 230v to 110v step down transformer you need. 1 day left on auction.

ahh kk dont need one so soon as uncle is not sure if he needs the item yet

http://www.hardwareforums.com/usa-uk-elec-mains-difference-printers-8976/
Check out that thread, could be of some use to you.