Erika is right that the most elegant and literary chastity belt would be mental. For those of us with more carnal than intellectual interest in controlling their man, there are half a dozen basic designs for preventing male orgasm (and dozens of slight variations), but all of the effective ones concentrate on preventing an erection. I can tell you from personal experience that if a man can achieve an erection there is no level of constriction that will prevent an ejaculation (in fact a poorly designed chastity belt could even hasten it).