XO Athletic Youth HeartShield Heart Protector Vest (Black, X-Small) Helps protect young athletes from "Comotio Cordis" - a rare but often fatal condition resulting from a hard projectile striking the heart center in between beats EDS Raised Tripod channels impact energy to the 3 anchor points, away from the heart area, greatly reducing injury potential Compression vest and "Tripod" design allow for complete arm motion with no restriction.