Description Designed for the river bottom at the Wild Animal Park in San Diego, CA, this pattern resembles real river rock. Corners of the stone are rounded and the average size of the rocks range from 4″ x 5″ to 7″ x 9″. The grout lines are extra deep for that true river rock semblance. Coloring with our Accent water based acrylic stain is a breeze. Stamp size 41.5″ x 41.5″. Package savings reflected in price.