Gentle Exfoliator for Soft and Smooth Feet. The NYK1 Smoothie Foot File is your go-to tool for achieving soft, refined, and freshly polished feet at home. Designed for gentle yet effective exfoliation, this smoothing foot exfoliator for hard skin helps reduce the appearance of rough, dry, or callused areas on the heels and soles. Ideal as a finishing touch after hard skin removal or for maintaining smooth-feeling feet between treatments.