Thank you Mosi customer service ! I was sent a replacement.Works perfectly! No leaks.Instructions for any new users out there, and save you some time :)1. Top shelf of dishwasher only.2. Not microwave safe3. Screw all removable parts securely ( not so tight as to break the threads!) but securely. The removable parts are all around the cover (sipper, strainer, rubber top)4. Make sure the rubber disk under the cover is also sitting tight and in position ( this is what makes the watertight seal)5. Close cap and put in FULLY locked position.6. Liquid level should be below the bottom of the strainerThe liquid is super hot which is a good thing. But if you are like me and don't like super hot tea or coffee , I remove the entire cover (strainer and all) and just drink it like out of a normal flask ie giving time for my tea to cool down a it. BUT.....when you do that make sure you do it over a SINK !This is because there is residual liquid in the strainer and if you remove it on the counter, or car, it will spill that residual liquid.Enjoy !PS: Mosi am waiting for a microwaveble version :) That way I can heat my milk in the same flask. :P--------------------------------------------------------Previous review follows below. This is before the replacement was sent. Mosi reckoned it might have been a manufacturing defect.Bought this Nov 2022. Writing my review now.I love tea but cant be bothered to wait for the all the waiting for it to brew and baby sitting a nice cup of builders tea needs, so this is/was godsend !However it leaks. I always thought it was user error ( the old Gen x mantra of 'Intel inside , idi...outside' ?)1. ensuring I am screwing the 2 removal parts securely2. not filling the flask with too much liquid.3. I mainly use teabags, have tried to swap it out with tea leaves.Leaks no matter what. At this point in time I do think it is not me, it IS the Mosi.There are pros but the biggest Con is the con :) it leaks.I am determined to use this because it is expensive, so I have put old (clean) socks around the bottle like a homemade koozie so when it leaks it goes on the sock and not all over my table and/or clothes.Pros-1. keeps tea hot2. dishwasher safe3. I love that the tea is not sitting in the leaves/tea bags steadily getting bitter and making it un-drinkable. This is why I bought this over all the other 'sitting in the liquid' tea flasks out there.suggestions: Wish it was microwave safe so I could heat my milk instead of using another cup to do that.