I have no complaints about this product. The OST Vitamin C20 serum comes in a sturdy dark glass bottle with a dropper. The product is slightly sticky on application. I was tentative to use it every night but my skin is not at all irritated by this product. Long-term use (as in, more than four weeks) brightened and evened out my skin tone and I would say that some very fine lines have all but disappeared. I keep this serum in the fridge. This product is known to be unstable but it was only a very light yellow colour when I finished it after two months, so keeping it in a dark cool space did the trick for me. I already repurchased this.