This is a very old exercise to enhance male sexual function. After the bathtub is fully warm and then out of the bathtub, apply cold water to the pubic area, stay for about 3 minutes, and then enter the bathtub after the penis and scrotum contract. So repeated 3-5 times can end, if you can insist on doing "alternating bath" every day, can make middle-aged men energetic, sexual functio... https://www.viagra-hk.cn