Newcomer needs guidance picking the right device for her partner

Hello all. My boyfriend of half a year mentioned he’s into this chastity kink. I’ve spent two weeks browsing around here and have decided to sign up. Before he brought it up, I knew nothing about chastity cages. Honestly, the concept didn’t click right away. He often jokes that wearing one will “give me powers,” and now I think I see what he means. It seems clear that he wants a cage for himself. What confused me was learning there are so many different styles available; I’m not certain which one to pick out. Which kind should I purchase for him?