The BLACKROLL GROOVE STANDARD has a rutted surface that creates a natural vibration. The grooves on the BLACKROLL will slightly vibrate when rolled, which improves blood circulation. The standard version has an average hardness and is appropriate for all ground exercises. It offers a strong massage and helps treat and prevent cellulite. This roller is environmentally friendly as it is made using an energy-saving production process and it is free of propellants and chemicals. The German-made BLACKROLL GROOVE STANDARD is easy-to-clean, water resistant and odorless.