After riding for about 800km to 1000km you need to change your bike chain. One can create a nice bracelet from that.
Jepp, that's jewelry for "men", made from steel, washed in acetone, brushed with brass, formed by a Dremel and oiled.
It will rust when it comes into contact with water. It will also react with sunscreen and stain your arm in orange. It will also attract other peoples attention.
Hint: Be careful, when traveling by Airplane this seems to be a dangerous device (???).