Purchased at BEAMS. There's no size tag, but BEAMS' official website has a similar knit cap, and it states the head circumference is 34 cm. I measured the inside with a measuring tape, and it was about 37 cm. I bought this for my child, but they've only worn it a handful of times, so there are no noticeable stains or frays. However, please understand that it has been stored in a closet for several years before considering a purchase. I plan to ship via Yu-Packet Post Mini, so I will have to compress it slightly.