All anti-rape devices are senseless and useless. Just teach your wife, GF, sister, mother etc. how to kill or maim a man. Don't think that women can't do it. As long as they get the idea, they can do it even more ruthlessly than a man. And remember, a man's weakest moment is when he's sexually aroused with an erection. Wherefrom do you think erection comes? The whole body of bloodflow concentrating on the penis rendering the rest of the body, especially fighting limbs, weak.
Just don't resist and yell insults and cause the man fury and fustration enough to lose erection and recover power of his limbs. In middle of his attempt, just go for the jugular or break one of his limbs. And from a legal standpoint, yes, killing or maiming a man in an attempted rape is perfectly legal.