Instruct: Classify Amazon reviews into positive or negative sentiment
Query: A pain to use

These inserts certainly work, but I will say that it takes longer to install them than the Drop-ins variety. I've not had any trouble with the Drop-ins leaking like some other reviewers (yet!!). I can see they will be easier to travel with since they are flat (as opposed to the drop ins which are round). I think I will keep both varieties on hand since they serve different functions.