I am currently testing the Cell Cycle Catalyst serum & am really impressed. The dropper is great for ensuring that you can dispense exactly the right amount of product each time & you only need a small amount to give an even coverage each time. I have been using it for a few mornings now & love the way my skin feels really soft & smooth after applying it. I have already seen an improvement in the fine lines above my lips, which is great. I have added it to my shopping list of products to buy & thank Skinceuticals for the chance to test yet another excellent product!