Fortress Building Products 10-ft x 4-in Black Sand Steel Post10 ft Black Sand Steel Post The Fortress Building Products 10 ft Black Sand Steel Post is engineered for exceptional strength and longevity. This low maintenance, fire resistant post is perfect for supporting decks made from any type of material including wood, composite, and aluminum, all while offering a sleek, modern aesthetic in a durable steel construction. Key Features: Sturdy Design: 10 ft, 3 1 2 in x 3 1 2 in post supports any deck type.