cb6000 compared to curve

Hi everyone, apologies if this topic has already been covered, but I’m looking for some guidance. My boyfriend’s birthday is coming up and we’re thinking of getting him a chastity device; it’s an idea that’s come up in our conversations over time. His measurements are roughly 4 1/2 inches long and 5 inches around when flaccid. Could the cb6000 be too tight? Is the curve likely to be excessive? I don’t have much experience with this, so any advice is appreciated. Thank you!