Not yet seen but question about how much paint it will hold?

I have not yet seen the Paintbook by EdgePro gear, but I can see a couple of potential problems with how much paint you can store on the palette? and with the apparently fiddly method for holding the panels. I don’t like removable pieces because they are so easily lost on painting trips. The removable glass palette idea though looks great as I like to load my palette up with paint and remove it in the evening to put it under water. This prevents the paint drying out.