Description of Under Armour Core 2 A/B Sports Bra - Women's The ultimate in comfort for "A/B" support during mid-intensity activity. Features: Outstanding HeatGear moisture transport Breathable mesh back panel Racerback design 5.3oz 81% PolyArmour, 19% elastane Mesh: 4.5oz 84% PolyArmour, 16% elastane