CXX X-Tra Strong is the toughest, strongest, most shock-resistant line on the market. If you're looking to throw into nasty cover for largemouth, battle huge tuna with your drag locked down to some ridiculous setting, or pull plugs for monster salmon in a raging river, there is only one line to trust.
Tournament anglers and guides alike choose CXX because of the abrasion resistance and its high strength to diameter ratio.