Stoneline Group SL32-D-B-674-36-30 12" x 24" Tundra Gray Marble Bullnose Leathered Coping. The Tundra Gray Collection stands out for its high-end modern style and luxurious looks. The cool tones of this natural stone bring to mind tranquility and a sense of durability. As a natural stone it matches well with a variety of styles, for modern to minimalistic or even rustic. The collection features a wide variety of styles from tiles and pavers to mosaics and veneers, your entire house is covered inside and out.