For that reason I didn't hesitate to buy the pendant "Time-Turner" that Harry and Hermione used it in the third book "Harry Potter and the prisoner of Azkaban" to save Sirius Black.
In the inscription can be read: "I mark the hours, every one, Nor have I yet outrun the Sun. My use and value, unto you, Are gauged by what you have to do."
The inner circles are mobile and hourglass, of course, contains sand. It hasn't an exquisite quality, but not bad at all.
And that's all for today, Thanks for reading!