The A3 Performance Sprintback is great for training and competition as it is made of the ideal blend of polyester. This style has thicker straps at the shoulder and more coverage on the back. Younger Sharks tend to like the thicker straps and more coverage. The Sprintback's incredible fabric provides great fit and color fastness. It is comfortable, lightweight and durable. The Sprintback will go the distance! 52% Polyester / 48% PBT, front lined.