Thank you for viewing. I purchased these for my kid's bicycle races and used them a few times. The FOX BMX long-sleeved wear, as shown in image 3, is labeled as Kids S, but it's a foreign purchase, so please refer to image 4 where I've measured it with a measuring tape. Also, the Under Armour item, as shown in image 8, I believe is similar to Uniqlo's Heattech, but it's labeled as HeatGear. The size is Youth M. Please check the measurements in image 9. I'm selling these as a set. These are used items and have been cleaned at home, so please refrain from purchasing if you are sensitive to used items. Thank you for your understanding.