Chirp Wheel for Back and Neck Pain – 3 pk: Plastic, EVA Foam, ABS, 500 lb Capacity Used twice. All 3 rollers - 10”, 6”, 4” The 10” Firm delivers targeted pressure to help you massage those problem areas along the spine, the 6” Deep Tissue digs in deep to get rid of your toughest knots, and the 4” Focus targets key pressure points in your neck to reduce tension headaches and relieve neck pain.