In the United States, roller skating gained popularity in 1935. However, it was in the 1970s when skating rinks playing disco music were introduced that roller skating truly became a sensation. Some of you may recall those heavy metal skates that could be adjusted as your feet grew. But do you remember the metal object that many skaters used to wear around their necks?

Images of this copper-colored object have been circulating on social media, prompting guesses that it might be a bottle opener or a tool of some sort. Surprisingly, it is actually a skate key – an important accessory for anyone who owned roller skates before the 1970s.

Using the skate key, skaters could adjust the size of their skates by fitting it into the back of the pair. To ensure they wouldn’t lose the key while skating, most people would wear it around their necks.