damn i bought mine over a year ago and mine didnt come with one =[
but i mount mine kinda unconventionally so idk if it would even work...
i mount mine on the bottom "beak" part of my helmet, right in the vent by the "chin" (this is on a MX helmet btw..) that way i dont have to worry about it getting ripped off the top or side of my helmet by a tree ( i race off-road, not MX)