This is an Adidas cycling inner boa jacket. The size is Japanese M, but it has a tight fit overall, and it was very useful as a winter jacket for children. I think it can be worn by children who usually wear clothes around size 150. My child wore it until they were wearing size 160 clothes. The back pocket has a zipper, and the neck and wrists are designed to block the wind, making it really warm. For reference, it's about the same size as a WAVEONE cycling jacket in size S. #ColdWeatherCyclingWear #KidsJuniorCycle #WinterCyclingJacket Size...M