Not that they’re metal. I’m assuming that it is in reference to the waistband that has a gold metallic sheen to it. Otherwise, I am not sure why these were called the metal line. They are super soft and comfortable, and really easy to wear. I had them in a few colours…not sure I still have them all though. While I love the material, I hate that there’s no pouch and these then end up squishing you. They have been in the TBD pile for a while and I think they’re getting passed on. I just am too old and have too much underwear to feel like I’m being squished by my briefs. 
Undies101 wants to know…don’t forget to vote in the poll!