A very versatile piece, perfect for spring, summer and autumn wear. The fabric is light weight, quick drying and will help to keep you cool on warmer days but offer you a little more protection than a short sleeve on nippy spring and autumn days. The sleeve length is really good as they are the length that most of us naturally pull our long-sleeves up to anyway. The colour choice is fantastic and will brighten up the greyest of days or sparkle on the long sunny days. A medium equates to a size 12. Great value.