These mirrors will attach to most modern bicycle helmets. The main requirement is to have a solid foam area approxametly1.5w x 1.25h inches available.  It has been brought to my attention recently that a few of the latest helmet designs, those with wide air scoop front vents, may be difficult to find enough solid foam to mount the claw upon. Specialized brand, women’s high end helmets are one example. Check your helmet and see if there is an area on the left toward the front that contains a large enough inch thick area to mount the Helmet Mirror on.