So you buy a metal bracelet and anytime you meet someone with the bracelet of the same brand you try to connect them. Most of the time they won't fit but if they fit that's it, there's no unlocking them, you are connected forever.

They can also lock two, three, four in a row so during your lifetime you create this small group of people that you share your life with.

It's called "wristmates" or something like that.