Vial
In short A vial is a small glass bottle with a rubber septum and a crimped aluminium cap. Research peptides are supplied freeze-dried in it and are dissolved again in it.
The septum reseals the container by itself after each puncture. It is what actually protects the contents, which is why the vial is best kept in its original sealed state for as long as possible.
Because a septum cannot be restored once removed, opened vials are excluded from the right to cancel. The details are on the cancellations page.
The closure consists of a rubber septum under a crimp cap. The septum is the real protection: it can be pierced and closes again afterwards, which is why a vial is not opened but pierced. Every puncture is still a strain, which argues for dividing the contents into small portions.
The size on the label refers to the nominal amount of the contents, not the capacity of the glass. A 10 mg vial is the same size on the outside as a 5 mg vial; how much solvent fits inside is a different question from how much substance it holds.
Vial sizes differ from substance to substance. Which substance is stocked in which size is shown in the price list.