Custom. My teacher client locks himself in chastity for 24 hours, with proof. Gave me his spare key, to play with, and secured his own, emergency key out of reach.

He enjoyed being locked away so much, I decided to be generous and extend the time period for another 48 hours. Bonus clips to go with it, too. I'm something. Remember when you were little and got a new toy, all you wanted was to play with it all day? That's how boys are to me. I will keep you as long as my heart desires, because you're my plaything and you'll do anything to please Mistress.