Someone recommended this product to me when I said I was suffering from severely chapped lips that were not responding to normal lip balms. And WOW, does this stuff make a difference! It's not quite as thick as regular lip balm (it's more like lip gloss) and it's not tacky at all like some balms are. Rather, it goes on very smooth. It also comes with a little applicator, but it's fine to just use your finger.
Anyway, you can wear this stuff night or day (you can apply lipstick over it), but it's good to apply a heavy coat of it for best results, and it really does help with badly chapped lips. Mine were in awful shape and they were nearly totally smooth after one night of wearing this stuff (a sugar lip scrub took care of the rough spots that survived).
It seems a little pricey for what it is - I believe I paid $8 for it - but a little bit goes a long way and that little container will last quite a while. I've had mine for at least two months at this point and it barely looks like I've used it after putting it on almost every single night. Also, I know this is generally labeled as a "berry" mask, but unlike many scented lip products, this one does not have a strong scent at all, even if you put your nose right in the container and take a big whiff. The berry aroma is barely there, so don't let that discourage you if you dislike products that smell.
Honestly, it's a beautiful product and I fully intend to buy another one when this one is gone. I think I saw something about a vanilla-scented one, which I would much rather have because it's one of my favorite scents!