Spike nodules balls provide deep tissue massage with acupoints stimulation to promote blood circulation and help reduce muscle pain, soreness, pain and nodules. Used at least once daily for around 5 to 10 minutes per each target skin area, helps loosen muscles before and after workouts to reduce risk of injury. Great for runners, yoga workout, office fatigue, driving fatigue and athletes recovering from sports related injuries or strains. 16 9/64" L