Matrix Dressage Competition Pad Pro 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 PairsPro Impact: For athletic performance and intense schooling. The ultra-light, ultra-thin layer of high density PoronR XRDTM provides superior concussion protection by absorbing 90% of the shock from impact. Perforated for breathability and treated with MicrobanR for antimicrobial protection. PoronR XRDTM is high performance open cell foam that absorbs most of the energy not only from the impact of the saddle on the horse's back, but also from the rider on the saddle. PoronR XRDTM protects the horse from impact and it minimizes the energy bounce back that a rider experiences when landing in the saddle, allowing for a more secure seat.