Why free?
Net profit is almost from nothing.
Grinding waste and casting the case and bracelet, yes, it costs money, but in such extremely modest volumes.
A child could solder two wires, a handful of diodes, and a swollen old battery. Also near-zero costs.
The disposal of the waste has already been paid for by someone to the manufacturer of this crap.
A bonus of $1.66 per piece comes from the stupid lava.
Transportation of this trinket is virtually free – you can use this junk as... what's it called, I forgot... filler... in short, you can simply fill gaps in containers with these bracelets and, on paper, treat them as packaging material.
And the environmental impact is negative – it won’t decompose in China, you can even rake in money for some environmental fund under this pretense.
In short, sigh...