I’ve used many C 15%/E/F products. Most of them irritate my skin, even tho other heavy acids (even .1% Retin A and 20% glycolics don’t bother me as I have very thick verrry oily skin). The only ones that don’t bother me are the skinceuticals C/E/F and the Photozyme. *however*, Photozyme isn’t just my first choice because it’s far cheaper and slightly less irritating. This product, given the addition of the DNA repair enzymes, is what makes it a massive stand out. I know a lot about anatomy, DNA processes, amino acids etc etc, and I can assure you that there is nothing else quite like this if you really want to repair your skin; topically, this is the best thing you can do. Adding supplements such as glutathione, astaxanthin, quercetin, resveratrol, nicotinamide riboside, 1000+mg hyaluronic acid, L-ergotheonine, collagen/elastin peptides, inositol, zinc and colloidal platinum plus other potent antioxidants/aminos Will really increase the results of any antioxidant topicals. While this formula is already amazing, I know they’re reformulating and I’d be SO excited to see *caprooyl tetrapeptide-3, L-glutathione, astaxanthin, resveratrol, FGF/other sh-polypeptides, nucleotides, ATP, or even perfluorodecalin or other PF’s that promote oxygenation*. I can’t wait to see the reformulation! This product was already advanced. I hope you read this comment and consider the suggestions! Thank you.