This is the same marine plywood decking used by new pontoon boat builders. CCA treated and designed for the rigorous marine environment. If you are planning to redeck your pontoon boat with 3/4" (in) plywood, this is the correct type of marine plywood you should use!
Most other standard types of plywood are treated with a copper compound that will interact with the latex rubber backing of your marine carpet and destroy it over time. This marine plywood is treated using Chromated Copper Arsenate (CCA) which is a chemical wood preservative containing chromium, copper and arsenic. CCA is used in pressure treated wood to protect it from rotting due to insects and microbial agents.