Sous Vide allows you to precisely control your cooking temperature to achieve perfect results. You can cook sous vide in FoodSaver bags by placing them in water at any temperature up to 195 F (90c). (Most sous vide appliances have built in temperature control but a cooking thermometer can be used to assure proper cooking temperatures are maintained. )
Food Saver bags and vacuum sealers are ideal for sous vide cooking as they remove all of the air around the food which ensures they will float less than ordinary zipper bags.
Using a FoodSaver vacuum sealer also ensures that all the air is removed which allows the heat to transmit better to your food. (Air is a poor transmitter of heat.)