When you need a greater capacity, the Nalgene Silo Sustain 48 oz. Wide Mouth Water Bottle is your ticket! It is leakproof and easily slides into packs and backpack side pockets. It is highly durable and features a standard 63mm loop-top cap. The neck configuration works with most major water purifiers and filters. Sustain bottles are made with 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.