ZOX Helmets Sizing Chart
Head Measurement	Centimeter	Hat Size	Helmet Size
20 1/8" – 20 1/2"	51 – 52	6 3/8" – 6 1/2"	XXS
20 7/8" – 21 1/4"	53 – 54	6 5/8" – 6 3/4"	XS
21 5/8" – 22"	55 – 56	6 7/8" – 7"	S
22 1/2" – 22 7/8"	57 – 58	7 1/8" – 7 1/4"	M
23 1/4" – 23 5/8"	59 – 60	7 3/8" – 7 1/2"	L
24" – 24 3/8"	61 – 62	7 5/8" – 7 3/4"	XL
24 3/4" – 25 1/2"	63 – 64	7 7/8" – 8"	2XL
25 5/8" – 26"	65 – 66	8 1/8" – 8 1/4"	3XL
26 3/8" – 26 3/4"	67 – 68	8 3/8" – 8 1/2"	4XL