What should collars be for intimacy?

I'm looking for a collar for my girlfriend right now. I want to give her such an unusual gift. Can you tell me which one to buy? Are there any criteria for choosing?

During sex and intimate play, collars for women should not squeeze the neck too tightly or restrict movement to avoid choking and skin damage. The material of the collar should be relatively soft and not interfere with your partner's breathing. When using a leash, it is important to monitor the tension and listen to your partner. Before using the collar for the first time, you should inspect the collar for sharp corners from jewelry and the reliability of the clasp or lock. On that site I think you can find something you like.

Take one that will sit well on the skin and leave no marks. Because poor quality collars can ruin everything.