There's something special about these slab trays. The clay is rolled out, and placed on a furniture cushion that's covered by a piece of fabric. Then a GR Pottery form mold is used to impress the shape. The fabric leaves it's mark on the back.
 
There are multiple layers of decoration using red iron oxide wash, stencils, porcelain slip and underglaze, and finally a clear glaze is applied.
 
The measurements are 12.25 in x 4.5 in x 1 in