What Cosimo linked is what you're after.
That said, I've never seen one of those with 4 ports, mainly because each motherboard connector only gives you two ports, and most motherboards only have one or two USB headers and usually one is taken for a front panel connection.
If you need more USB ports than your motherboard can supply, either from the standard I/O backplate or from onboard headers, your options are limited to either an add-in card such as the one linked by Archerz above, or USB hubs which plug in to one of your current ports but typically give you 4 ports in return.