The Markwort Youth Heart-Gard Body Shirt features a tough, high density polyethylene dome that absorbs impact energy and forces it away from the heart. It is small in size, measuring 6" x 6", yet safely covers this vital area. When wearing this compression shirt, the Heart-Gard is discreet and does not restrict movement. It's comfortable and cool, so kids forget they are wearing it. Please note: May not completely cover 100% of the vulnerable area on larger players. Larger players should purchase the original Heart-Gard (HG-CS) with adjustable straps for proper fit. 80-85% Nylon and 15-20% Lycra. High performance compression shirt with Heart-Gard sewn in. Heart-Gard is protective and absorbs impact energy, forcing it away from the heart. Dome measures 6" x 6". Discreet, does not restrict movement. Cool and comfortable fabric wicks away moisture.