This product is a 80ml of VG pre-filled.

Vegetable Glycerine (VG) is a commonly used ingredient in various products, including cosmetics, food, and pharmaceuticals. It is important to note that VG is intended for its specified uses and should not be ingested in its concentrated form.

DIY Aroma Guide
Remove the Lid
Remove the Top Cap
Pour 80ml VG in the 120ML bottle 
Replace Top Cap & Lid
Shake Well to Mix