ISDIN SI-NAILS Nail Strengthener & Cuticle Moisturiser - Repair Serum for Weak & Brittle Nails - With Keratin & Hyaluronic Acid - Invisible Finish, Results in 14 Days, 2.5ml ISDIN Si-Nails is an innovative nail treatment that has been clinically proven to strengthen brittle nails by increasing thickness, density, and durability of the nail and cuticle. Supplies the nails with more keratin, more hydration, and promotes silicon - meaning your nails become stronger and more protected. Contains cationic hyaluronic acid, which promotes hydration in the cuticles. Easy to use, with a click-pen applicator dispensing serum that absorbs quickly with an invisible finish. To be applied over clean, dry nails (do not use over polish).