Proline Decorative Concrete Systems SL600F 24" x 48" California Weave Belgium Slate Concrete Stamp. A highly unique pattern, Prolines California Weave has a background texture of Belg Slate. This pattern offers stones measuring a square of 8 Inch surrounded by 8 Inch x 16 Inch bricks. The edges of the bricks are moderately chiseled for a natural stone appearance.