I just got a roor ashcatcher for my baby
An ash catcher is like another filter added before the bowl!
Its far easier (usually) to clean an ash catcher than an entire bong. So an ashcatcher also keeps all that nasty shit from getting in and dirtying up ALL the glass
On the back of that ash catcher you posted rzza, the glass on glass joint fits in the bong, and then the other higher female end is where the bowl goes.
The picture you posted is an inline ash catcher, sort of a funky design. The smoke fills up the first chamber, then moves into the round chamber through the slits into the water, then up and down and into the bong.
The gold ball on top of my bong is an ash catcher that doesnt filter, but works REALLY well. It keeps the roor glass and hurricane clean, and the ash catcher bulb takes less than 5 mins to clean it spotless
I have the easiest bong to clean ever
Do you like benassi?