... Roller material: Zinc-alloy and a grade ABS LED: 6pcs a grade LED Item No.:868N Product naem:Wrist ball ... like golf,tennis,squash,cricket,baseball,bowling,basket ball,motocross,mountain climbing.-Increase strength in fingers, ... and joints.GENERAL PRECAUTIONS:-Do not drop the ball on hard surface at any time , the ... heavy rotor will damage.-Do not touch the ball rotor when it is spinning at high speeds ...