Coolers are insulated portable containers designed to keep food fresh and beverages cool. Coolers are available in a variety of sizes, materials and styles, ranging from a small, lunch bag cooler to carry bottled water or any other drinks, to a style that looks more like a picnic basket. Bag style coolers are made of soft materials and can be folded up for easy storage. Bigger coolers are often study and compact and may feature wheels for easy transport.