A man’s anatomy is a lot easier to understand than his mind, and knowing what’s going on down there is just as important to a happy relationship as figuring out the deeper meaning of his every word. You can analyze your relationship with your girlfriends, but who can you turn to with the more . . . sensitive questions? In Size Matters, Dr. Harry Fisch, an expert on the male reproductive system, and writer Kara Baskin team up to introduce you, metaphorically speaking, to the penis.

Clearing up mysteries about male anatomy, orgasm, masturbation, STDs, testosterone, impotence, sexual response, and much more, Size Matters is the first women’s user manual for male sexuality—a guidebook that will answer all your questions and lead you to a better sex life. For example:

Can masturbation have any effect on sex? Can he do it too much . . . or too little?
He always orgasms before me . . . is there any way to slow him down?
Do grown men still have wet dreams?
Can his weight affect our sex life?

Size Matters is a fun, prescriptive, easy-to-understand troubleshooting guide for women who have questions about male sexuality or who want to have better sex. You might not always understand what’s going on in his mind, but now you can know what’s going on in his pants.