DetailscapCAP is the civilized 2-in-1 accessory cap designed to work with Nalgene, CamelBak, and most other popular wide-mouth drinking bottles. The new, re-designed capCAP+ is also compatible with Hydro Flask wide-mouth, Nalgene Stainless, and Guyot Stainless. Most wide-mouth bottles are easy to fill and clean, but the standard opening is too big to drink from without spilling. Narrow-mouth bottles are great to drink from but you can forget about putting ice cubes in them, let alone cleaning them. And bottle inserts don't really fix a spout that was never meant for daily drinking. capCAP offers the best of both worlds. Drink spill-free through the small spout, and then clean and fill easily with the large cap. Don't forget that the wide, rounded strap is more comfortable to hold too. The new capCAP+ has a few additional cool features like the "CapKeeper" that holds the small cap out of the way when drinking and rubberized grips on the small cap. capCAP+ is 100% BPA-free, polycarbonate-free, and phthalate-free. Both caps are made with FDA-approved, food-safe polypropylene (#5) plastic. It is also covered by our lifetime warranty.