The Meheen fillers are built for one bottle spec. If you use a O-I 12 oz. long neck, the machine is built for that one bottle. You can not switch to another 12 oz. long neck without purchasing a whole new top end.
The machine is able to do 12 & 22 oz. bottles if you purchase two top ends. Last I heard $5000+- each, one included with a new machine.
It is a good, dependable unit.