The TriggerPoint GRID, the original hollow core foam roller, features a patented multi-density foam surface that is ideal for beginners to advanced rollers. Designed to optimize mobility and enhance recovery, the GRID delivers firm compression while channeling blood and oxygen needed to repair muscles. Proprietary Distrodensity zones replicate the feeling of a massage therapist's hands, helping to relieve tight muscles, knots, and kinks for a total-body massage