After the first serum vial, purchased on the basis of rave reviews from one of the users a good impression. I have oily skin, dense and porous. therefore, irritation or tightness serum did not cause, use the first tube are quite happy-skin became more smooth, the pores narrowed slightly. However, a friend bought on the advice of my second tube proved to be of a different quality - serum was mixed texture -That is too thin or too thick, and almost did not work, a friend did not see any effect. I could not believe it and bought a tube of the third in a row - and surprised, yes, the texture is heterogeneous, and is a major inconvenience, accounts for more squeeze to apply properly to the face. Efficiency has also decreased, the feelings. It seems that the product is either expired or changed the formula. More will not buy, alas. Put 4 only for the first successful tube.