As common for all bottles containing a liquid, it is vital that there be ullage, a space between the liquid and the neck of a bottle.

It is necessary for any bottle containing a liquid to contain this space, allowing for the expansion of the liquid as temperatures change, or during any type of transportation.

Each flacon from Xerjoff contains the exact amount of perfume indicated on the label.

Flacons are purposely manufactured to be larger the amount of liquid it needs to hold in order to purposely allow for ullage.

Any flacons which are produced containing smaller capacities are discarded directly by the glass manufacturer.