We haven't used the filters yet, as we don't yet need them, but we are happy to have them "on deck" for when we do. We do love our water filter unit and it works great! Thanks for the quick and efficient packaging and shipping! The hand-held portable water filter unit with carrying cover is lovely, but seriously, we cannot get the top to come off. We have both worked in construction for years and one of us has an engineering degree, so we aren't mechanically challenged! I am wondering if it got overheated in transit and somehow welded together? We have given up trying to open it for the time being! If not for this issue, we would have given 5 stars in the rating!