With its Polartec Alpha insulation, created for the demands of high-intensity exercise, the Defend Fire Alpha Jacket is all about keeping your temperature regulated. Despite its low bulk and low weight, it doesn’t a brilliant job of holding on to body heat. However, it’s also superb at preventing overheating and sweat buildup, allowing excess heat to escape as your effort levels rise and fall with the terrain. The result is greater comfort on the bike. The Defend Fire is also made to be tough. The outer is made from a durable stretch Cordura material, more than a match for the demands of mountain biking. The stretch fit and MTB-specific cut also ensure you’re never held back from throwing your bike around the trails. And then there’s the DWR (Durable Water Repellent) treatment, shrugging off mud and water kicked up off damp trails.