Unique straw lid always keeps the sippy nozzle clean and provides much healthier drinking condition for you and your child! Extra Accessories: Bundles hydro standard mouth flask straw cap accessories include one straw lid, one carabiner, 2 straws, and 1 straw cleaning brush. Trim straw to fit your hydro standard mouth bottle; The Alloy Carabiner is great to hold items, ideal for hanging your bottle on the bag and ropes, etc. Brand New Design: New and Improved Double Wall Insulated Straw Lid for hydro Standard Mouth flask bottle ( mouth diameter is 1.91 in) and simple modern narrow mouth stainless steel water bottle with 1.88 inner screw mouth diameter. Perfectly fits on Hydro flasks 12 18 21 24 OZ Standard Mouth Bottles. Insulation: Inspired by the bee nest, our double wall structure creates a vacuum space that will help insulate your water cold for a whole day and hot for 12 hours. Extra Large Mouth Piece: Our unique oval-shaped mouthpiece effectively increases water flow by 50% than the other models on the market, perfect for any type of beverage and powdered drinks. Leak-Proof Guarantee: Yes, we are so proud of our design that we can guarantee 100% leakproof if the lid is in the closing position. Our food-grade silicone connector will hold and seal the straw which creates an absolute vacuum for you to suck up the water with ease.