The Inkey List Collagen Booster Firming Peptide Serum Collagen naturally plumps and firms skin and The Inkey List Collagen Booster Firming Peptide Serum (£9) mimics that same result with its peptide instead. Image Source: cultbeauty.co.uk The Inkey List Collagen Booster Firming Peptide Serum £9 from cultbeauty.co.uk Buy Now