Matrix Dressage Competition Pad Lo Impact Inserts are sold in pairs to fit the pockets in your Matrix Dressage Competition pad. Matrix Biokinetic Inserts offer customized back protection for the horse using the T3 principles of ergonomic design and advanced technology. Every Matrix Competition Pad comes with a Velcro spine to accommodate inserts so the rider can switch inserts for different horses or different needs using the same half pad. Using separate inserts for the left and right side of the pad allows space in the middle for spine clearance and free movement of each side of the horse's body for greater comfort. Sold in PairsLo Impact: For general riding and schooling, low impact training; especially beneficial for horses that are in a conditioning program. Also recommended for horses with back issues. This low density viscoelastic foam mimics the density of muscle tissue, offering a wide, supportive base without restricting or inhibiting movement. Allows for expansion of soft tissue required to condition and build muscle, therefore creating an environment for optimal muscle conditioning. Because of its thickness, Lo-Impact does not dissipate heat as rapidly as the Pro-Impact. It's use is confined to low impact riding where its cushioning properties are most important.