As Caroline Hirons has said; just buy this product. This serum is paraben and fragrance free (two big ticks for me) and contains hyaluronic acid which is found in the body and naturally absorbs and maintains water in the outer layer of your skin leading to hydrated and plump skin. What I love about this serum is that it doesn't have any bad ingredients in it or is gimmicky; it simply does what it says it will do and leaves your skin feeling moisturised and soft. It is not sticky at all, the packaging is lovely (who doesn't love the bright pink text?) and it is the perfect travel size to take about with you. It is a gel consistency and I use this morning or night or both before my moisturiser and it works wonders. Just buy it. Seriously.
This is one I picked up in France and it has a thin, milky consistency. It is absolutely great for dehydrated skin, instantly packing moisture back into your skin. It sinks in pretty quickly without leaving any oily residue and I think this would work on any skin type. It does not irritate my sensitive skin despite the fact that there are fragrances and silicones on the ingredient list so you should be pretty safe with this serum. I prefer to use this one at night as it does take a little longer than hydraluron to sink in and it feels a tad more hydrating.
Have you tried either of these? What are your skin saviours? Let me know in the comments below.