First time I have pruchesed product from Medik8 and that was Tetra C serum. It was recomanded to me by my bestie as she is working with these cosmetics and she loves them! So I thought I'll give it a go as my previous serum from other company (overpriced but popular) has just finished. I decided to try just simple Tetra C and I'm amazed by it. Its very delicate, silky in touch. My skin absorbs it quickly leaving delicate smooth invisible film. Its clear in colour and just 4 drops every morning are enough to cover face and my neck. I will combine this serum with day cream from Medik8 as I want to change my daily face care and after using TetraC I'm convinced I'll be happy from all Medik8 products.