During sex with a doll, have you ever experienced your penis being pushed out by the strong air pressure inside the doll?
The zero-reverse-thrust vagina can solve this problem very well，
You can think of it as a breathing vagina.
I believe that when you have sex with your doll,
your penis will feel an inexplicable outward pushing force,
which makes you consume a lot of energy during the exercise.
Inadvertently, it will be difficult for your penis to continue to rub in the vagina, and it will come out of the vagina.
This is because the vagina of the doll is a closed environment, and the air inside will block the penetration of the penis.