Hydro Flask has you covered with the Standard Mouth Flex Cap. Built with Honeycomb insulation, this cap works with any standard mouth Hydro Flask.
• Compatible with all Standard Mouth bottles
• Honeycomb insulation™ helps keep cold drinks cold and hot drinks hot
• Durable, stainless steel pivots allow the strap to move easily
• BPA-Free and Phthalate-Free
• Lifetime Warranty