These are so useful! Prevent the dust, sand, dirt, mud, water, bugs, and anything else from finding its way into your drink! Also prevents spillage when having your out door fun! Great for trail sodas while riding and even to save drinks at the campsite or on the beach. We use these all the time and they are my top seller at Busco Beach. Small for glass bottles and Large for your cans! Can tops snuggly fit right on both standard can sizes and slim cans as well!!!