Originally made to be a charcoal￼ filter, but i don’t have the charcoal anymore. U can get it at your local smoke shop or on amazon. 
it can also just be used as an ash catcher placed before your bong 
or if u wanna full send that shit and fill the whole thing up w flower it could b a massive bowl😂
comes with a 18mm and a 14mm cleaning plug made by grav aswell worth 10 each
Left is 18mm to 14mm (20$)(Scientific Inhalations)
Right is 14mm to 14mm (20$)(Grav)

Adapters