The BLACKROLL DUOBALL massage ball is the ideal tool for self-massage and body rejuvenation. Its purpose is to relieve muscle tension and reduce ligament sprains. The use of a massage ball reduces scar tissue adhesions and ligament sprains in the long run. Diameter 8 cm Intended for point deep muscle and tissue massage The distance between the two balls allows for a purposeful and effective massage around the spine and the Achilles tendon Improves muscle flexibility and efficiency For upper arm chest neck and calf muscle massage Intended for use on a table floor and wall Usage: Slowly roll BLACKROLLDUOBALL back and forth 6-8 times putting pressure on the ball thus improving blood circulation reducing muscle tension and ligament tension.