Nailner Pen Nailner Pen is an easy to use precision pen applicator that is clinically proven to treat & prevent fungal nail infections. It provides fast visible results & protects the newly grown nail from infection. Nailner Pen treats nail fungus by saturating the keratin layer of the nail & lowering the p H of the infected nail to create an unfavourable environment for the fungus, inhibiting growth. Nailner Pen can also be used once daily to help prevent fungal infection of the nails. Nailner Pen contains Approx. 400 applications.