321 STRONG Foam Roller - Medium Density Deep Tissue Massager for Muscle Massage and Myofascial Trigger Point Release, with 4K eBook 12.75 inches x 5.25 inch diameter , lightweight yet rugged solid core EVA massage roller with triple grid 3D massage zones mimics the finger , palm , and thumb of a therapist's hands . Travel friendly at just 1 lb . Medium density muscle roller is comfortable to use - making it easy for beginners , but still effective at penetrating the soft tissue layer of tired muscles . Soft enough to use while in pain from lower back injury , sciatica or plantar fasciitis . One of the best recovery tools to treat muscle pain , increase performance and flexibility. Rolling before and after exercise sis part of a great stretching routine . Increases blood flow to massage site , flushing away stored lactic acid . Stretch overworked and strained muscles of the leg , arms , and feet by rolling during your warm up and cool downs . Provides instant benefit to the hamstring , IT band , glutes , and calves by delivering superior massages at home or in the gym . Loved by runners , Crossfit athletes , yoga and Pilates students , swimmers , physical or sports therapy patients , and those just doing a normal fitness workout . Great for the arch of the foot , and any part of the body but the spine or neck . Protected by US Patents 9,345,921 and 9,656,112 - eBook arrives as email attachment, also available from manufacturers website.