Designed to develop and maintain the strength and dexterity of your fingers, hands, and forearms, the D'Addario Varigrip features an ergonomic design and variable tension that is customizable for each individual finger. The reversible molded grip even uncovers simulated strings to help develop and maintain finger calluses when you are away from your instrument. D'Addario Varigrip, the ultimate conditioning tool for musicians. Note: Varigrip is an exercise product. Stop use immediately and consult a health care professional if you feel pain or discomfort while using the product. Excessive use may cause pain or injury.