If I can elaborate...the presses with floating top platens are able to lock down evenly on thicker items. The press' top platen will level off prior to making contact with the substrate loaded. This platen feature eliminates the pinching effect that has plagued clamshells for years. The floating lower platen also eventually levels off but the back portion of the top platen will meet the substrate first, then it levels off. Not that this is a huge deal on most applications, but on some thicker items it can have that pinch effect.The platen self levels to adjust for substrates that are not truly flat. say one end of the substrate is 5/8th in thickness on one end and the other end is 7/8th; the press will adjust for this variation.