They do have a slight bow to them allowing the most pressure to be put onto any high spots when you push down. The croc scrapers are heavy duty and very versatile and can be used for cleaning, keying, scraping and flattening almost any material. We have got some footage that I need to process of the scraper in action, but I am without the mac for a couple of weeks.
The scrapers also come with a tapered front end allowing you to get into awkward corners and spaces that are otherwise very difficult. I've just noticed that the 13" picture on the website is wrong, he 13" looks slightly different, with the handle set back in the same position but with an elongated front end, specifically designed to get into awkward corners and spaces without your hand getting in the way.