FEX WRISTOR Classic-Series Power Essential Spinner Gyroscopic Wrist and Forearm Exercise Balll with Blue LED Light - Blue Patented design,battery-free version. Cool LED lights inside will light up while spinning, no battery needed. Computer balanced inner gyroscopic rotor for VIBRATION FREE operation at up to 15,000 RPM Small, compact exercise machine you can take ANYWHERE; Provides up to 25.9 pound-in of torque at 10,000 RPM. Impact Resistant structure with Military-grade plastic shell. Reversible inner tracks make 2X Lifespan. Simple to start with a pull-string (2 strings are included). Have fun while relieving carpal-tunnel and arthritis symptoms. Use as a strength and coordination builder.