I thought for the summer season I would grab one of those cheap eBay mesh/armour jackets. I did some measuring, checked the size chart and I ordered the corresponding jacket for my skinny ass. When it arrived, the sleeves ride up my forearms, the elbow cup sits on my triceps and its impossible to zip up .. I contacted the Chinese seller who decided to mess me about for 6 weeks, then eBay stepped in and gave me a full refund. It was obviously not worth the seller arranging for its return. So, it's up for grabs - I don't think it would fit an adult rider but OK for someones child, possibly a small Thai lady - leave a message here and I will forward FOC ( obviously in Thailand ) The size on the label is M, when I checked other sellers advertisement they equated a size M to XS.