NSD Power Essential Spinner Gyroscopic Wrist and Forearm Exerciser Exercises Wrists and Hands  Spins at up to 15,000+ RPM to exercise and strengthen wrists and hands; Youll feel the burn in just a minute of spinning Smart Design  Patented NSD Power Spinner is small and compact but provides ample resistance via angular momentum for an intense workout; generate 26.8 lb-in of torque at 10,000 RPM Simple Operation  Easily turns on via the included pull-string so you can pick it up and get started Rugged, Long-Lasting Design  Made with a military-grade plastic shell, a break-resistant structure and reversible inner tracks for 2X lifespan Easy To Use  No batteries required; You can get a challenging, strengthening workout anytime, anywhere, even on your lunch break Precision Made  Computer balanced inner gyroscopic rotor with stainless Steal axle; ; Compatible With Nsd Digital Speedometer Sm-01 and Sm-02