I have had just about every type, style, and option of insulated thermos, cups, and bottles.In my opinion, there was a lot of thought put into the design of this one. I do not often leave reviews, but for this one I will attempt to better explain the logistics of why each feature that I can appreciate actually has endless negative reviews on.PRODUCT REVIEWS, WHEN IT COMES TO NEGATIVE REVIEWS, OFTEN REFLECT A MISUNDERSTANDING OF FUNCTIONAL PURPOSE/ USE/ OPERATION.My intention is to show that every negatively review I have read is just that. LID / LEAK-PROOF / STRAW / AIRTIGHT SEAL :▪︎ STRAW~It is a 3-piece straw with simple assembly. ALSO, IT IS NOT TOO SHORT, NOR TOO LONG FOR THAT VERY REASON!! The silicone tip that goes at the bottom can be adjusted to fit correctly. AIRTIGHT SEAL & ONE-HANDED open/close FUNCTION ALOND WITH THE (optional) STRAW ALL WORK TOGETHER SIMULTANEOUSLY! (One you understand that then you will see the purposes in the overall design) LEAKPROOF / QUARANTINED AMOUNT OF TIME TO HOLD HOT & COLD FOR SPECIFIED TIME***With the flip top lid closed this thermos has a 100% airtight seal***THE ONE-HANDED FUNCTION OF THE LID MAKES IT QUICK & SIMPLE TO CLOSE IN BETWEEN SIPS. This is helpful in all of these features, and more!☆ it may be helpful to try using without the straw for a short while to get in the habit of doing this☆ALSO, THIS APPLIES TO THE COMMENTS ABOUT THE LID BREAKING EASILY, BEING PLASTIC (there is no need for a different material than plastic for the lid either! The small rubber stopper on the inside closes again the tip of the straw... creates that airtight seal, and serves as the final part that helps to retain heat & cold) { yes, it's on the heavy side, but not when you consider the insulation, size (compare ounces capacity with your other insulated mugs and you'll see that this was holds more volume), and materials} LASTLY, THE ATTACHED PHOTO OF THE LARGE, DOUBLE SILICONE ICE MOLD IS MY SUGGESTION FOR ANY ELSE WHO WILL BE USING THE THERMOS AROUND THE CLOCK... ☆ #6 ⚫️ and #6 ⬛️ ice cubes 5cm in diameter. I ONLY HAVE TO ADD MORE ICE APPROPRIATELY EVERY 24-30 HOURS ☆ ALSO, AS FOR IT NOT HOLDING ICE VERY LONG:¤ ARE YOU USING A TYPICAL/ STANDARD SIZE ICE CUBES? IF SO, HOW MANY?These are high volume (they hold far more than most insulated mugs & thermos! Check the capacity of volume in most every one and you will better understand why you may need to start with more ice in these.ALSO, PEOPLE, PLEASE DO TAKE A MOMENT TO CONSIDER THE LOGISTICS BEHIND PRODUCT DESIGN SO THAT YOU CAN GET THE MOST OUT OF THE PRODUCT ITSELF!IT'LL SAVE YOU FROM FRUSTRATION, DISAPPOINTMENT, TIME, HASTLE & SPENDING MONEY UNNECESSARILY WHEN THINGS DO NOT WORK AS ADVERTISED & EXPECTED! AND IT WILL HELP THE MAKERS OF THE PRODUCTS AGAINST NEGATIVE REVIEWS THAT MAY NOT BE VALID! please remember also...When you purchase online, make sure that you are reviewing correctly! Is your review of the product, the packaging, the shipping, or the seller themselves?Label it as such so that others can determine what you have stated, why, about what OR about whom?MORE OFTEN THAN NOT YOU WILL GET YOUR ISSUES RESOLVED MORE EASILY, MORE QUICKLY, MORE EFFECTIVELY, AND TO YOUR SATISFACTION BY SIMPLY MAKING CERTAIN THAT YOUR CONCERNS ARE PROPERLY ADDRESSED!Companies do not make money by ripping their customers off! A solid company makes money off happy, loyal, repeat customers!They do, however, loose money from people claiming that their product is bad, or the features are not as advertised simply because you did not take a moment to consider whether or not you may understand its functionality.