Serum are like magical drops that give nourishment to your skin. The packaging has a volume of 50 ml.
From OnBuy
Biotherm Aqua Source Deep Serum Deep Moisture and Light Concentrate - All Skin types - 1.69 oz Serum
The product is available from £33.26 at international stores.
Parfumdreams
Biotherm Deep Serum Female 50 ml