Here is a very cool Vintage All Sport brand Snowmobile - Motorcycle helmet from the early 1970s. Made of General Electric LEXAN polycarbonate resin that is 8 times stronger than fiberglass.These helmets were adjustable by adding padding inserts. The inserts were not in the box so it is still set at Large. This helmet was adjustable from 6 7/8 to 7 1/2. Model number is 460538. They are very similar to, and compatible with most of the early black and yellow Ski-Doo clothing. http://dollykamco-the-private-collection.auctivacommerce.com/Vintage-1970s-All-Sport-Snowmobile-Motorcycle-Helmet-Lg-P1429965.aspx