The Nalgene Kid's Sustain 12 oz. On The Fly Water Bottle features a leakproof loop top that swings open to reveal a contoured, high-flow drinking spout that is easy to fill at the fountain or sink. It has a one-handed push button that allows for easy open/close and contains a locking bail for ultimate leak protection. Sustain bottles are made from material derived from 50% plastic waste. Each bottle is created from resin powered by next generation recycling technology that transforms plastic destined for landfills into high-performance bottles.