Ultra C Firming Serum
左旋維C-20緊緻精華液

I used the product for a few days and my skin got irritated by it, started with itching and then it got really dried and eventually I got marks where I scratched myself.

Not only did it not help with firming, but it got me going to the dermatologist several times now, and even though I stopped using it for 3 weeks now, my face is sometimes still itchy and the marks are still there. The derm said it was too strong, triggered by skin so it will take some time to heal.