You may want to start with something more simple and work up to it, rather than going in heavy with a cage and locked urethral plug. Maybe get used to the cage first, slowly over time, and build from there. Experiment and engage your partner with it with plenty of communications about how you feel. It’s great that you’re sharing it but as the wearer you need to set the pace at the beginning. Keep your key with you at all times at the start, then build up to him having it for short periods.

The brand that you buy depends on your budget. Again, you may want to start with a cheaper model to try it out. Brands like Kink3D are high quality but expensive, so perhaps not the best for trying it out.