The slit is like opening of the urethra in the glans penis. In the human male, the urethra is about 8 inches (20 cm) long and opens at the end of the penis. The urethra provides an exit for urine as well as semen during ejaculation. When the penis is erect during sex, the flow of urine is blocked from the urethra, allowing only semen to be ejaculated at orgasm. The external urethral orifice is the external opening or meatus of the urethra, normally placed at the tip of glans penis; it presents as a vertical slit, possibly bounded on either side by two small labia-like projections. In some cases the slit may be more rounded. This occurs naturally in some males and may also be a side effect of excess skin removal during circumcision.