Grid Foam RollerThe GRID 1. 0 foam roller features a hollow core design for durability and an easy to clean EVA foam surface, along with patented GRID pattern that replicates a massage therapist's hands. GRID PATTERN Replicates the feel of a massage therapist's hands in three unique ways HOLLOW CORE CONSTRUCTION Durable design maintains its performance after repeated use PREMIUM EVA FOAM Comfortable feel and easy to clean JUST RIGHT PRESSURE Provides the most