Mistress Ava makes a living selling chastity devices and chastity keys. She knows a lot of girls would like to control their men and she offers a solution to that. She provides them with a means to control their man and to ensure they remain faithful. They lock the devices and keep the keys. They only allow them a small room to use in peeing. They cannot even get boners as it would be painful.
Princess Serena loves to tease because it makes her feel powerful. But she knew that her new man was weak and he could not avoid temptations from many women. She was traveling for work but she did not want to take him with her. So she ordered for a new chastity device that she got him to wear. She then went with the chastity key to make sure he would not open it and fuck anyone while she was away.