Seriously, who needs to record someone without the knowledge of the person being recorded? That’s a big red flag, a perverted character, there’s no other explanation. Creepy Mark Zuckerberg allowed other creepy characters to share personal moments with him.
Doing an Internet search, they are about the same price.
Or you could just use a cheap camera (might be less expensive than the hard hat) or your work phone. (Free) They also have the benefit of not being fixed to your head and a viewfinder so you know exactly what’s in frame.