Knotty Tiger JR Roller Massage Ball. This little Knot Buster® roller ball can help relieve muscle soreness and stiffness. This is our therapy-clinic-grade massage tool used most often by massage therapists for chair massages. The massage ball rolls easily over clothes and skin while saving your hands and fingers from fatigue. This tool simulates the therapist’s deep tissue elbow massage technique. Massage therapists love adding essential oils to this tool. Small, lightweight, and portable so you can bring it anywhere!