Flat wiper blades are fast becoming the standard fit on new vehicles. These types of wiper blades do not have a metal 'coat hanger' shaped frame. Instead they have a tensioned metal strip running within the rubber structure of the wiper blade. This design allows for a flatter aerodynamic shape which reduces wind noise and offers a superior wiping experience.
If your vehicle is factory fitted with this type of blade you can not replace them with a conventional blade. The wiper arm will have a different set of fittings for the blade. There are several different types of fitting depending on the size and shape of the blade. Some wiper blade suppliers produce exact fit blades with the same type of fitting for the vehicle where as others offer less wiper blade options and offer a selection of attachments to aid with fitting depending on the wiper arm on your vehicle.