A very useful glass roach made from laboratory-grade borosilicate glass. The flat end serves several functions. It means you are toking on glass instead of paper which is much more pleasant. It provides a firm grip and and also helps cool the smoke.
You can either use the entire tool as a large roach, wrapping the paper around the outside, or use it more like a holder carefully pushing your pre-roll into the end of the filter.
The roach is easy to clean and infinitely reusable.
These are in some ways similar to our Carbon Filters so they are worth checking out as well.