The Hydroflask 21 Oz Standard Mouth features TempShield insulation and is the ideal go-anywhere companion. The bottle keeps cold up to 24 hours and hot up to 6 hours. It is the ideal combination of strength and flexibility. It has replaced the existing cap on all of Hydro Flask's Wide Mouth bottles. It is specially designed for ultimate portability. It is made of 18/8 Pro Grade Stainless Steel and is BPA-Free and Phalate-Free.