You will only be able to buy these palettes from this website. The Palette shape and size is the equivalent of A4. Made from plastic.
As these items are made of plastic.
Terry especially designed this palette; he tried to create 'The Perfect Palette' for watercolour artists. The whole idea being that the lid is placed over the paint wells enabling the tube colours to remain moist and workable and help preventing them from drying out between painting sessions. It saves wasting paint by washing it away after a painting session and enables you to transport your unused paint without a mess.
The large mixing sections are divided into three so that you can group your colours, for example, earth colours in one section, blues in another and so on. The front of the mixing area slopes upwards to avoid spilling and making cleaning easier.
These palettes have no base are not air tight.