International Swimming Pools Z19818 4' ZAM® Steel Left Side Panel with ExT Holes - This panel is for use in in-ground pools. It features ZAM® metal coating technology. ZAM® steel is coated with zinc, aluminum and magnesium for maximum corrosion resistance. Due to its strength, durability and eco-friendly features, ZAM® is used across a number of industries. This material exhibits an exceptional alkaline resistance, even in direct contact with concrete and mortar. Salt spray testing has proven ZAM® has protection in salt and other severe environments. This makes it an ideal choice for saltwater pools!