New Balance Men's Short Sleeve Ace Baseball Jacket With fabric designed to trap body heat and provide lightweight warmth for those all-important pre-game rituals. Because how you perform before the game is as important as how well you play. You take warmups seriously because you know they make your game that much better. Post-game cool down is just as important to your long-term success. With a soft 3D stretch woven fabric, the Short Sleeve Ace Jacket provides much needed warmth and mobility for all stages of the game.