The watercolor palette insert is an accessory for the sienna plein air pochade box. Two sizes of palette are available to match the two sizes of pochade box. Two rows of well line each side of the palette. There are two large mixing wells to keep warm and cool colors separate. A lid is included to cover unused paint. The watercolor palette is held in place with the large set of palette blocks included with the pochade box. The M watercolor palette has two mixing areas that each measure 3 in x 6 ¾ in, four 1 in x 1 in wells, one 1 in x 2 in well on each side of the palette.