Modular polo mallet head design

Inside diameter changes depending on the class. Outside diameter stays the same (so you can use the same fittings for all classes for a given size).

Yep, but could that be dependent on material? All the talk above is about ABS, the heads Lucky is making now is HDPE, similiar to the water and gas pipe we use.

Gabes, that's amazing that it's used in tattoo inks. I've known that some tattoo inks are similiar to auto paint, using the same pigments but plastic? Polo mallet plastic? That's creepy.