Straw Lid for Hydro Flask Standard Mouth Water Bottle. New and Improved Design Replacement Cap for 1.91" Mouth Insulated Water Bottle 12 oz, 18 oz, 21 oz, 24 oz. Compatibility: Our straw lid will replace Hydro Flask standard mouth lid for sports water bottles and many other standard wide-mouth vacuum bottles with a mouth diameter of 1.9", please measure before purchases. New and Improved Design: Double-wall construction, our straw lid provide an extra layer and completely insulated the bottle. Advance craftsmanship for strong, durable yet smooth handle for easy carry. Extra-wide straw and mouthpiece make sure your drink flows effortlessly. Leak-Proof: We use the highest quality food-grade silicone gasket and connector to ensure 100% leak-proof when closed the lid, so you can rest assure with the bottle laying in your backpack. Perfect for Outdoor Activity: Our straw lid turns your average Hydro Flask into an easy to drink sports bottle, open and close with one hand only. No more twist and turn!