It's a finger banger. It's designed to use your finger as the carb cap, and the hole in the side is to spin your terp pearl. I'm guessing they are figuring people are too afraid to actually use their fingers, so provide a carp cap. It is a china copy of this banger...
I find like anymore than .2 .3 starts to give to much icky tasting vapor. I kind of prefer to load just a tiny bit more than I can take in one hit, so that I can feel like I got the biggest hit possible, but not alot of Dookie hits to finish it.
Yeah I was aware of the strength and volatility of terpenes. I wasn't sure if the dosage settings went small enough to even make that a possibility. Just late night brainstorming.