Vitamin C Ampoule, bought with my own money

This is the innovative concept pure vitamin CE ferulic acid serum.

It comes in a small size that's perfect for using within a month or two, so there's no risk of throwing it away due to discoloration. The price is also affordable, so you can apply it freely without worrying about running out. You can choose the concentration from 15% to 20%. I'm using it alongside a Vitamin A product, and since this is my first time using it, I chose the 15% concentration without being too picky to ensure a smooth adjustment period. It's the best value item for beginners!