Are the straps solid or stretchy? Do you think I could fit this on my hardhat for work?
They are stretchy. Sorry I do not have a hardhat to try it on.
However looking at the unit, I see a sturdy curved mounting plate that could be screwed on to a hard hat. Just drill a couple small holes and add some nuts and bolts.
That might be a better solution than relying on straps to hold it. The weight is 3.5 oz. with the straps
I think it might be a splendid addition to a hard hat. See the photo.
Since you get 3 of them, you can use one for your hat and one for peering down the shell casing to make sure your powder is all there. Plus an extra spare.
Like Martha Stewart would say, "It's a good thing."