A everyday serum featuring tetrahexyldecyl ascorbate, a stabilized, low irritation form of vitamin C. Suitable for all skin types , C-Tetra is ideal for those new to vitamin C. Tetrahexyldecyl ascorbate is an oil-soluble, super-stable form of vitamin C which retains its power throughout its use. The vitamin C is combined with co-antioxidant vitamin E. C-Tetra helps to promote a visibly brighter complexion while reducing the appearance of skin aging signs . The lightweight, jojoba-based formula with a fresh citrus scent sinks in rapidly, leaving skin looking refreshed . Medik8 recommend a simple, effective skincare strategy of using vitamin C and sunscreen in the morning and vitamin A at night. This strategy is called: CSA.