The GLX 104 series has a destinct copter sytle look with an lightweight ABS thermoplastic resign shell, plush interior and a unique shield and base plate making it one of a kind. A removable neck curtain has also been added for all riding conditions and better comfort in warm and cool climates. It is available in 8 different color options in sizes from XS-XXL. For proper fit and size measure the circumference of your head 1" above your eyebrows and around the largest portion of the back of your head. 20 7/8" - 21 1/4" =  X-Small; 21 5/8" - 22" = Small; 22 3/8" - 22 3/4" =  Medium; 23 1/4" - 23 5/8" = Large; 24" - 24 3/8" = X-Large; 24 3/4" - 25 1/4" = XX-Large. DOT Certified.