Youth Large Backalast warm up jacket/posture corrector. According to PBT's website: a revolutionary posture-correcting compression jacket designed specifically for dancers. Backalast's mission is to help dancers strengthen thoracic spine strength and assist them in finding the neutral position for the head, neck, and shoulders. The jacket is made from a breathable compression fabric that stretches in four directions and is cleverly equipped with multiple layers of mesh support to enhance awareness of key posture corrections. It emphasizes the neutral position of the scapulae, prevents the occurrence of winged scapula, and provides a stable foundation for arm positioning. It runs very SMALL. This would fit an average 7 to 8 year old and is VERY tight. (My daughter was 10, but she is very tiny.)