Portable Pocket Guitar F Chord Trainer Practice Tools Guitar Finger Exercise Jig for Beginners Guitar AccessoriesF Pocket Guitar Chord/Finger Strength Trainer and Expansion Exerciser. For beginners, it is difficult to play the F chord. It can also practice your fingers while practicing the F chord. And it is helpful for other chords. LED error notification, if your gesture is not correct or the strength of your finger is not enough, the LED will not be on. Power Supply: 1 x CR2032 BatteryProduct Size: 18 x 4.6 x 4.2cm Product Weight: 100g Color: Black Material: Plastic Package Contents: 1 x F Chord Trainer1 x User Manual1 x CR2032 Battery Manual1 x English Manual Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement error is +/- 1-3cm.