The center's concave shape avoids direct pressure on your spine or neck. With raised sides that align with your muscles this deep-tissue massage roller provides safe targeted relief along your back and neck. The textured surface of this vibrating peanut massage ball roller mimics finger kneading targeting tight muscles precisely. With 4 adjustable levels 1500 to 4200 RPM it fits all recovery needs. This peanut roller ball massager combines durability with portability.