The Ordinary's Multi-Peptide Hair Serum for Hair Density is a leave-in hair serum aiding in the look of thicker, fuller hair. Having already transformed our skin care regimes, we could only dream that The (extraordinary…) Ordinary would branch out into hair care – and, with this Multi-Peptide Serum for Hair Density, they have! According to the brand itself, this concentrated formula ‘is designed to support hair health so that it looks thicker, denser, fuller and healthier’ – all words we’d very much like to use to describe our own (occasionally lacklustre) locks. So, how does it reap these miraculous results?