Wolfride Finger Exerciser Trainer Hand Strengthener for Guitar Bass Piano or Therapy Help develop and maintain finger calluses for string musicians Compact and Ultra-light design, you can practice without your instrument anywhere anytime Quickly and Safely to improve your strength, endurance, flexibility and coordination Soft button cap makes it comfortable to press, also non-slip and sweat-resistant, The slim size makes you hold it all in one palm Not only design for musical instrument, but for practicing the hand fingers strength, like Computer Operate, Climbing, Yoga, Gaming, Bowling, Fishing, Martial Arts and etc.