I needed a good SPF as I use retinol at night. An essential was that it worked well if I wore makeup, with no flaking, as too often I had found what can only be described as pilling in some areas when I applied foundation. And of course it had to offer excellent sun protection. I read about Coola in an article by an independent beauty writer and it's everything I wanted. It melts into my skin over moisturiser and if I do wear makeup I don't have to wait for the sun screen to be absorbed.