A Ball:No LED,No Digital display
B Ball:Colorful LED, No Digital display
C Ball:5 challenge color,Digital display
D Ball:6 challenge color,No Digital display

Challenge Color:As the speed changes, the color changes

Digital Display Feature:
1.【Record total number of revolutions】
2.【Record instant transfers】
3.【Record Top speed】
4.【90s/60s/30 Countdown】
5.【5 challenge colors】

Other Feature:

1.Make Arm Great Again. Strengthen fingers, wrists, hands, forearms, shoulders, and bicep, etc. It also can be beneficial in promoting co-ordination and blood circulation.
2. The dominant hand/arm was easily able to keep the gyro ball going, that it will help refine you're fine motor skills in that non-dominant hand/arm.
3. Small, compact and transportable, you can take anywhere. Simple to start with a pull-string.And we have a flashing LED style,all you need do is to increase the speed by making a rotational wrist movement and to keep in sync with the spinning of the ball.
4. The unit did not have any weird vibration to it. Also having the silicone grip section is very nice as it helps with the gyroball not coming loose from your hand. You can attach it to a wrist strap if you are really concerned about the gyroball flying away.

Bullet Points:
1【Ideal For Sports Lovers】The Finger Strengthener can improve the finger strength of athletes (rock climbing, fitness, tennis, baseball, boxing) and musicians (guitar, bass, pianist, and violinist) and daily housework ( driving, typing, writing, working, etc.).
2【Portable And Lightweight Design】Finger Trainer is small and light enough to fit in your gym bag or pocket. You can enjoy a workout at work or at leisure. Exercise your hands anytime, anywhere with the Finger Extensor Exerciser.