YONEX Warm-up Jacket with Lining A must-have warm-up jacket for badminton and tennis. This is a beautiful item. Manufacturer color notation: Black/Acid Yellow Heat Capsule: Warms up by infrared rays. A heat-generating system that converts sunlight and infrared rays emitted from the human body into heat, trapping the heat inside the fibers. When irradiated with infrared rays for a certain period of time, the surface temperature differs by approximately 3 to 7°C compared to conventional cold-weather materials. Specifications Heat Capsule, anti-static, reflective, water-repellent, full motion 3D, hem spindle specification