> "I'm pretty sure the outside is aluminum, fyi, unless they make multiple types. The inside part is probably steel." The original standard Hydro Flask is, exc

> "I'm pretty sure the outside is aluminum, fyi, unless they make multiple types. The inside part is probably steel." The original standard Hydro Flask is, except the lid, entirely Type 304 stainless steel (aka: 18/8 steel), powder coated on the outside.