Brand Forceball Model SPT-ALC Quantity 1 Color Blue + black Material Plastic Functions Enhances the strength and flexibility of fingers wrists forearms biceps triceps and ligament Best use Multisport Other Features Theory: It is application by centrifugal force and inertia like a gyroscope; Dynamic: There is no any batteries or electricity inside the device. It is powered by rotating the wrist and the speed of rotation can reach over 8000RPM; Perfect exercise gadget for sports like golf tennis squash cricket badminton baseball bowling basketball motocross mountain climbing; Increases strength in fingers wrists hands forearms biceps tricepsligament and shoulders; Great benefit for musicians guitarists drummers; Rehabilitates sore muscles and joints; Built-in LED it will light blue under high speed rotating. Packing List 1 x Force ball 1 x Started rope (40cm) 1 x Wrist rope 1 x English user manual