Yeme Grey Variable Tension Hand Finger Exerciser Grip Trainer for Music Instrument Resistance adjustable from 3.0 - 8.5 lb on each finger, thereby allowing a single unit to meet all of your exercise needs. Innovative 5-Button design allows finger extension exercises, critical for piano and guitar players. Perfect tool for pre-show warm-ups and maintaining conditioning when away from your instrument Precise design for spring structure with copper nut and screw, and the product has a lifetime warranty.