I have high hopes for this serum, but unfortunately her I failed. Just a couple of days after the start of use I noticed on the brush mold spot. What was to blame, it is not clear - the serum was stored at room temperature, however, on the packaging there are no special recommendations for storage. Shelf life was in order. May cause damage to the product has become a long transport in transit. It is a pity, since the composition of serum from promising. Serum is in a closed metal tube in the form of a pencil with a brush on the end. Serum gets on the brush by unscrewing the bottle before the drop. I hoped for the best with this serum but failed. I saw a spot of mildew on the brush in a few days after I started to use it. I keep the serum at room temperature and I do not know what caused it. However, there is no special storage conditions on the label. Expiration date was OK. I think the cause of spoilage could be a long expedition time. I am very upset. Serum is inside a closed metal tube like a pen with a brush. Liquid gets on the brush after turning the bottom of pen.