2XU Apparel Size Chart THe MCS Cross Train Sleeveless Top provides targeted support for the obliques and lower back for all forms of cross training and HIIT (high intensity interval training). Its compression fabric helps improve your performance with increased circulation, reduced fatigue, and faster recovery times. Ideal as a base layer, with complete freedom of movement through the arms. Features: - Lightweight yet powerful PWX fabrics - Durable yarns that outlasts the competition - Multi-directional stretch - Flexible & breathable - Moisture wicking yarns to help keep you dry - UPF50+ sun protection - Antibacterial - Fabric (Front): PWX 70D. 72% Nylon / 28% Elastane (Invista LYCRA(R)) - Fabric (Back): PWX 105D. 65% Nylon / 35% Elastane (Invista LYCRA(R))