Angelina about a little more than one million men (assuming equal numbers of women and men in germany) 42 million men /100*2.5 = 1.05 million
I would say even this is to high. I would still substract all male minors (approx 8 millionsΒ²). So 36 M/100*2.5 = 900,000 men.
And if you look about how many devices are sold. Remember one male can buy more then one device (e.g. "what have you done if your old belt" ).
And the male customers haven't to be in a heterosexual relationship. I think in the homosexual community chastity devices as play tools a far more existing.
Β²https://www.bpb.de/nachschlagen/zahlen-und-fakten/soziale-situation-in-deutschland/61538/altersgruppen