Glycerin dab coolers help to cool the vapor of your dabbing experience. The glycerin dab cooler can be put in a freezer and then you can use it like you would an ash catcher for for your dabs.
There is no filtration when you you use a glycerin cooler as the tube does not go trough water. As much as we love glycerin coolers we find a dab rig to be a better buy. There is for sure a time and place for a glycerin cooler though.