I don't think there's such a thing as a comfortable chastity belt for men. Would seem to me that there are far more comfortable female chastity belts for women than there are for men. A little arousal can bring a tremendous amount of discomfort for men. I don't want to sound like I'm complaining because all I'm doing is trying to state an observation. Some dominant woman, i.e. keyholders are a little more proactive than others when it comes to their slave's chastity devices. I would say that most want the slave to be at least a little (but not too) comfortable when they're locke...
