The ALPHA Ball TWIN Set is your go to travel roller. Two 3.5" diameter Roll Model massage balls in a perfectly sized snug-grip tote provide a massive amount of shear and grip. Whether it's neck traction, spine rolls, QL, IT Band, hips, buttocks or other large muscle mass, the curves of the two ALPHAs together allow for deep, precision rolling. Use it against the wall or on the floor.