The Ordinary Multi-Peptide Serum for Hair Density The Ordinary Multi-Peptide Serum for Hair Density ($18) packs three different peptide complexes to improve thickness and fullness. Beyond adding density, this product also helps increase blood flow in the scalp so that — and follicles — are well-hydrated so hair grows in healthier, too. Image Source: sephora.com The Ordinary Multi-Peptide Serum for Hair Density $18 from sephora.com Buy Now