Hydro Flask Wide Mouth Flex Cap. Strong yet flexible, the Wide Mouth Flex Cap is the perfect companion for spontaneous campouts, epic road trips, and everything in between. Made with stainless steel pivots and an easy-to-carry strap, this cap has Honeycomb Insulation™ to help keep your drinks cold for up to 24 hours or hot up to 12. Pair it with any of our Wide Mouth bottles. BPA-Free and Phthalate-Free. Lifetime manufacturer warranty. Imported.