Matrix Lo-Impact Inserts are most suitable for low impact training and conditioning for general riding and schooling. Also recommended for horses with back issues who are actively rehabilitating. Designed to go inside the Matrix Half Pad. This 1'' low density viscoelastic foam cushions the back but allows the soft tissue of the back muscles to expand so the muscles can rebuild and remodel.... (read more) Once the back is well on its way to developin, switch to the Pro-Impact or Ortho-Impact for higher intensity training or performance. Sold as a pair. Fits both Traditional and Ergonomic Matrix Half Pads. Dressage.