There are three things you can rely on once you've laced up your running shoes: a fast pace, plenty of high-octane action–and your Mens Air Lock Jacket from Jack Wolfskin. This innovative training jacket is extra warm, weighs hardly anything and delivers outstanding breathability performance. Perfect for winter sports! Everything about this jacket is geared towards keeping weight to a minimum–including the ultra-lightweight Pertex shell fabric and the innovative mesh fleece lining. It consists of hollow fibres with a cross-section that looks like an eight-pointed star. The big advantage is, it weighs less than other fleece fabrics but provides better insulation. The fabric's knitted-like structure makes it extremely breathable. It is also air permeable. Exactly what you need when you're trying to improve your PB on the fitness trail.