As seen on the Harry Potter movie series.
According to Harry Potter Fandom:
A Time-Turner is a special timepiece in which an Hour-Reversal Charm has been encased, for added stability. It is a device used for time travel, and it resembles an hourglass on a necklace. The number of times one turns the hourglass corresponds to the number of hours one travels back in time (although, it should be noted that the longest period that may be relived without the possibility of serious harm to the traveller or to time itself is around five hours).
Harness your inner Hermione with this lovely gold-plated piece.