Black Leaf quartz oil bowl

 This Black Leaf QUARTZ Oil Bowl has a central tube. 

It's as easy as that: Put the bowl on the bong, heat the oil pan red hot with a burner, let it cool off for a short time, then put some oil or wax into the pan with the respective tool and take a draw while smoke develops! 

The bowl is made of quartz glass which is in comparison with borosilicate glass durably heat-resistant - the heat is kept better and longer. Signs of wear which show with borosilicate glass when heated very hot and used very often are not to be expected as quartz glass shows little thermal expansion and high thermal shock resistance.