Head Measurement	Size
51 cm - 52 cm / 20.1 in - 20.5 in	X-Small
53 cm - 54 cm / 20.9 in - 21.3 in	Small
55 cm - 56 cm / 21.7 in - 22.0 in	Medium
57 cm - 58 cm / 22.4 in - 22.8 in	Large
59 cm - 60 cm / 23.2 in - 23.6 in	X-Large