The website address you gave does not bring anything up, but I can tell you a bit about case presses based on my experience.
I own two presses. One has brass dies and the other has white plastic dies. I prefer the plastic dies as the brass ones can scratch your watch, even when you place cloth between the die and the face of the watch.
To close the case on a watch with a square crystal, you need to be able to fit the die around the crystal and catch the case of the watch. If the die makes any contact with the crystal of the watch, it will absolutely break it. When you are shopping for a case press, take some measurements to make certain that the case press kit it has a die that will fit over the crystal.