The TriggerPoint GRID Foam Massage Roller is THE original hollow core roller! It features a patented multi-density foam surface that delivers firm compression like a sports massage while channeling blood and oxygen needed to repair muscles. The GRID Foam Massage Roller is the go-to roller to release muscle pain and tightness, improve mobility and increase circulation. This roller is recommended by sports doctors, chiropractors and physical therapists The three-dimensional surface allows tissue to aerate while you roll, promoting the flow of blood and oxygen needed to repair muscles. Proprietary Distrodensity zones replicate the feeling of a massage therapist's hands. The hard, hollow core hand-wrapped in EVA foam makes it firmer than traditional foam rollers. Its superior construction won't break with repeated use. Ideal for both beginner and advanced rollers.