The tool in the photos is the next step up from the basic card scraper, the card is held in the metal body which stops your fingers getting burnt when the card gets hot! The flat sole also means you can scrape right up to the edge of the workpiece without worrying about the card catching the edge.
There is a screw on the back of the tool which allows you to increase or decrease the amount of flex in the blade, this effectively governs the depth of cut!