Revolve Advanced Water Filter for Hydro Flask Eliminates up to 99.9999% of all fresh water contaminants including Giardia & Cryptosporidium Features straw cap for easy and quick drinking Threads easily into the Hydro Flask 21oz bottle Produces more than 75 gallons of clean-tasting, filtered water Though Hydro Flask is proud to offer a lifetime warranty on all of its products, we cannot guarantee claims made by third-party companies