The Quadrant offers great performance and excellent comfort in a lightweight design. Built to exceed both DOT and ECE 22.05 standards, the Quadrant is truly a world-class helmet loaded with features normally found on more expensive helmets. Featuring a dual-density expanded polystyrene liner, extensive venting, molded roost guard and a plush removable liner, the Quadrant offers comfort and performance in a lightweight package that’s got great balance and a secure fit.

Thor and Pro Circuit have a legendary history together and now you can run the Quadrant Pro Circuit helmet that features the same graphic scheme as the team helmet. Join the Monster Army and run the officially licensed team graphic.

Size	Inch Around	Hat Size	cm
XX-Small	20-1/2	6-1/2	51-52
X-Small	20-3/4 - 21-1/4	6-5/8 - 6-3/4	53-54
Small	21-5/8 - 22	6-7/8 - 7	55-56
Medium	22-3/8 - 22-3/4	7-1/8 - 7-1/4	57-58
Large	23-1/4 - 23-5/8	7-3/8 - 7-1/2	59-60
X-Large	24 - 24-1/2	7-5/8 - 7-3/4	61-62
XX-Large	24-3/4 - 25-1/4	7-7/8 - 8-1/8	63-64