Under Armour ColdGear Base Layer Trousers Mens. Under Armour ColdGear Base Layer Trousers MensThe Mens Under Armour ColdGear Base Layer Trousers are perfect for cold weather training days, crafted with a wide elasticated waistband and flat lock seams that provide a comfortable fit. ColdGear technology helps to trap warm air and hold it against the skin and the design is complete with Under Armour branding.