I'm a Maxi pouch, I have 8 built-in rubber slots for essential oil bottles and can be expanded or maximized to 15-18 bottles as it has extra room in the middle.
 
Suitable for long travel usage as you may need some extra essential bottles as a back up and obviously it needs space to store. 
 
The maximization of the space is depended on how you mixed the size of the bottles.
The pouch fits to standard size of essential oil bottles from 5ml, 10ml or 15ml.
 
The size of Maxi Pouch is 11 x 6.5 x 20 cm