Shellstone 12x18 (1.25" thick) Double Bullnose Coping: Expect shade variation. All natural stones must be sealed. Sealing is an absolute MUST to guard against salt attack on salt water pools, as well as water penetration that can affect the durability of the stone. Buyer must determine that the product's slip resistance is acceptable for an outdoor application. *Freeze-Thaw Warning: NOT recommended for climates where severe freeze-thaw cycles are experienced.