With contributions by CB3000. - Thanks!
Modern Chasity devices are used now primarily by men as an element of a Chastity Fetish.
I feel that male chastity is becoming more and more common. One day soon women will require male suitors to belt up and hand over the key as a true sign of their commitment before the woman will allow them to see them.
I offered to wear one when I asked my wife to marry me, because her past boyfriend and husband both left for the other women they were having afairs with. Today I think she requires me to wear it all the time to keep me from masturbating and hence keep all my desire to serve her.