Si-Nails nail strengthener is a clear, lightweight serum delivered by an easy-to-use, one-click applicator pen, applied once a day. Use on dry, bare nails for best nail repair results. The first time you use ISDIN Si-Nails, activate the brush by pressing down on the applicator until the brush is moistened (approximately 25 times). Visible results may be seen in 14 days, with best results achieved from ongoing application. Use only on the nail, and wipe off any excess product from the skin.