ISDIN Si-Nails Nail Strengthener 2.5ml is a clinically formulated serum designed to enhance nail health by increasing thickness, density, and durability. Its key active ingredients include Silanediol Salicylate, which delivers organic silicon to support nail growth and strength; Pistacia Lentiscus (Mastic) Gum, known to stimulate keratin synthesis for improved nail structure; and Cationic Hyaluronic Acid, offering superior adhesion to nails and cuticles for prolonged hydration. The lightweight, fast-absorbing formula ensures an invisible finish, making it suitable for daily use. Visible improvements in nail condition can be observed within 14 days of consistent application. ​