NPT WNSB104 12" x 24" 5cm Walnut Bullnose Coping. Whether creating a patio, a walkway, or a pool deck, NPT natural stone hardscapes are the perfect fit for your pool area. The natural beauty of travertine and marble are ideal for any outdoor space. So, make your outdoor living dreams come true with sizes, colors, patterns, and textures to fit every taste.