ISDIN Si-Nails is an innovative formula that helps promote nail growth that has been clinically proven to strengthen brittle nails by increasing thickness, density, and durability of the nail and cuticle, Visible results from 14 days. Nail strengthener developed specifically to protect and improve the appearance of your nails. | ISDIN Si-Nails Fast Absorbing and Hydrating Nail Serum Strengthener, 0. 08 oz | Dermstore