It is part of the incentive of getting a dominant I guess, you get a bit more freedom in the collar choices.

[He casts a quick glance at the rest of the bar before he reaches up to pull his own off and show it to Reno. It is expensive looking, clearly handmade. The black tooled leather is covered in gold in places. And it looks like it is made to choke if you pull on the ring. ]

I picked it out, I am sure Tseng is happy to let you decide on your own. It doesn't have to be this big either. It just have to clearly be a collar. And last I checked you can take it off inside your home.