This sleeve can help keep your drink cool on a sweltering day hike or insulated on a chilly winter adventure. It's a nice snug fit for the Nalgene Tritan and HDPE bottles. It will also work with any 3.5" diameter bottle. Fits perfect with the 48oz. bottle, or you can drop its top for the 32oz. bottle. The best part, it's reversible! You can either get noticed with the bold orange on gray face or flip it and go incognito with gray on brown.