As an undereye mask, this does the job. If I'm having a really late night, I place the hydrogel patches under my eyes and they take care of the puffiness I would otherwise have. I can't say whether they lighten my dark circles though; maybe one has to use them longer for that. Still, this is a good product if you're dealing with undereye puffiness.  

feel relaxing when using it

It literally makes my dark circles disappear. Plus it can be re used by putting it in the hot water tub for bathing. Also, it comes with a spatula.