I am very happy with the Boosters of Paula's Choice. Have now received the C15 Super Booster. Still use it with Paula's Choice's Calm series. Find it similar to most vitamin C products I use only it is a lot stronger on the skin. It first gives a tingling (is of course also on your skin) that mine is sensitive and dry but after that it feels so refreshing? Have used it for a few weeks now and I notice my skin is alive again? Get color again! Ben really pale. It penetrates well into the skin and you really only need a few drops. Pat it especially where your skin needs it most. I don't do this under my eyes because I'm already a bit thinner 👵 and am very careful with some stronger serums! All in all definitely a must again!