The unique shape of the circle hook keeps the hook from catching in the gut cavity or throat, resulting in higher survival rates for released fish. They work by allowing the fish to take the baited hook, and as the hook is reeled in, it is safely pulled out of the fish until it reaches the mouth. At this point it will catch the corner of the mouth of the fish, resulting in less fatalities. The smaller size hooks are ideal for pike and catfish, and the larger sizes are great for catching cod, pollock, conger and tope. Can be used for both freshwater and saltwater fishing.