Asics im 12 zip topthis inner muscle half zip top with short sleeves and tight fit will help to increase your running capacity by improving your posture with its stretch diamond shaped panel technology at the back features84 polyamidenylon 16 elastanespandexbreathe easier by keeping your shoulder blades in the correct position opening up your chest and straightening your spine for improved lung capacity easier arm swing and better breathingstay dry with advanced lightweight materials