Isdin Si-Nails Nail Strengthener for Healthier Nails. KEY FEATURES: ‣ Fortifies and revitalizes weak and brittle nails. ‣ Contains hyaluronic acid, cationic hyaluronic acid, and silk peptide. ‣ Promotes nail growth and improves nail resistance. ‣ Easy brush-on application with a 2.5ml compact bottle.