I also use Hyaluronic acid and natural and organic rose hip seed oil (natural retinol) in my serum and its amazing. The ultra fine l-ascorbic is so g=difficult to find regionally. I received 90g for 27 USD (shipping and all) bit pricey but it goes a good distance. Michelle D. https://mysitesname.com/story4343986/the-single-best-strategy-to-use-for-make-vitamin-c-serum-from-orange-peel