Just fyi, I measured the HD20 at 87 grams, far less than the 130 grams specified (no battery). I weighed the HD20 and the head strap at 132 grams. More details with pics here: https://budgetlightforum.com/t/-/62231/296
That's a confusing spec - if it was taken with the strap then it should be mentioned. Otherwise it seems better to use the weight without the head strap. Everyone thought this light was too heavy because of what was specified. I looked and couldn't find the true weight in any of the threads or reviews.