The capCAP+ is the civilized 2-in-1 accessory cap designed to work with Nalgene, CamelBak, HydroFlask wide-mouth, Nalgene Stainless, Guyot Stainless, & most other popular wide-mouth drinking water bottles. Also features the "CapKeeper" that holds the small cap out of the way when drinking and rubberized grips on the small cap for easier opening. 100% BPA-free, polycarbonate-free, and phthalate-free. Both caps are made with FDA-approved, food-safe polypropylene (#5) plastic. Universal (63mm)