✅FUNCTIONAL--It is specially designed for Fits 32oz 40 oz Hydro Flask water bottle stainless steel wide mouth water bottles and the other brand water bottles in the same wide bottom diameter(Size: 3.56inch bottom diameter, 1.89 inch high). ✍NOTE: Don’t fits Owala FreeSip, Twist, Flip and Stanley 32oz 40 oz Tumbler! ✅SMART IDEA--No noise any more when landing your flask on desk and protect your flask bottom from damage. Bright up your Hydro flask and get a new looking for your favorite flask! ✅BPA FREE--Made of high quality food grade silicone material, feel safe to take it as a dog bowl on-the-go activities ✅PORTABLE TO CARRY--Reusable, washable and foldable. Our sleeve can withstand stretching, folding, and anything life throws at it 😊SATISFACTION GUARANTEED--Buy with confidence! You are assured to get the products as described and get the quick/easy customer service by wiring or talking to us directly About HEYSKAY flask silicone boot-BPA free soft silicone material-Fits Hydro flask perfectly and the other brands which diameter is the same as Hydro flask like as Simple, Mira, Yeti (note: a bit tight for Yeti but ok to put on) Bright up your Hydro flask look-No noise any more when landing your flask on desk and protect your flask bottom from damage, smart idea!