TRIGGERPOINT Performance Therapy Grid Patented Multi-Density Foam Massage RollerFoam Patented foam roller design offers a superior, multi density exterior constructed over a rigid, hollow core Constructed from quality materials that wont break down or lose shape from repeated use Includes access to free online instructional video library on foam rolling best practices from the experts at trigger point Trusted foam roller of physical and massage therapists, coaches, trainers and athletes Original Grid: Standard density, 13 x 5. 5