NOTE: In some cases, the D-ring on the helmet's strap might be a tight reach to the lock clasp. There's an optional accessory we call a HELMET ANCHOR that is very useful in these situations. it is an anchor-shaped aluminum bracket with a hole on top. You slide it through the D-ring on the helmet and loop the hole part through the lock clasp. (The last photo above shows this Helmet Anchor).
Here is the link to our Helmet Anchor (part# HLA-B):
https://www.ebay.com/itm/267463954157