CB-6000 fit a 4-5 inch soft cock?

I’m struggling with getting the right measurements for a chastity device. At first, I was leaning toward the Curve model, but I wondered if part of my shaft might stick out from the top opening. Am I right about that? My main concern is spending $150 on the Curve only to have it slip off. Also, while I’m okay with a chastity belt (CB) for its non-sexual benefits for my wife, I don’t want one designed purely for torture; so I worry the CB6000 might be too small. What do you all think? P.S.: Personally, I think the CB6000 sits better on a shaft than other models. (No joke)